Updated on 8/3/2023 with link to updated Legal Pneumatic Parts article in the VEX Library.
The following descriptions, examples, and images may help clarify the intent of the VRC robot inspection rules. Understanding these details and edge cases is recommended for inspectors at all events, particularly Signature and Championship Events.
Rule R4: Robot Sizing
Robots must fit in a sizing box. Robots must be able to satisfy <G5>, and begin each Match in a volume smaller than 18” (457.2 mm) long by 18” (457.2 mm) wide by 18” (457.2 mm) tall.
Red box for <R4>: The official sizing tool [the On-Field Robot Expansion Sizing Tool] is intentionally manufactured with a slightly oversized tolerance. Therefore, any contact with the sizing tool (i.e., a “paper test”) while being measured should be considered a clear indication that a Robot is outside of the permitted size. This tolerance also provides a slight “leeway” for minor protrusions, such as screw heads or zip ties.
Rule R5: Robot Safety
Robots must be safe. The following types of mechanisms and components are NOT allowed:
- Those that could potentially damage Field Elements or Discs.
- Those that could potentially damage other competing Robots.
- Those pose an unnecessary risk of Entanglement with other Robots or the Net.
- Those that could pose a potential safety hazard to Drive Team Members, event staff.
Check that robots have no sharp or jagged corners that could cause harm to people, or to the field and its elements (nets, etc.).
Rule R6: Robots are Built from the VEX V5 System
Robots may be built ONLY using official VEX V5 components, unless otherwise specifically noted within these rules.
Official VEX products are ONLY available from VEX Robotics. All official products are listed on
There is a wide range of discontinued VEX V5 products that are still legal for use in competition. These are listed at https://www.vexrobotics.com/v5-discontinued.html.
Rule R7: Legal Non-VEX Parts
Certain non-Vex components are allowed. Robots are allowed the following additional ”non-VEX” components.
Any material used as a color filter or a color marker for a legal sensor, such as the VEX light sensor or the VEX vision sensor.
Images of the light sensor and the vision sensor.
R7b & R7c
Any non-aerosol-based grease or lubricating compound, when used in extreme moderation on surfaces and locations that do NOT contact the playing field walls, foam field surface, Discs, or other Robots.
Anti-static compound, when used in extreme moderation (i.e., such that it does not leave residue on Field Elements, Discs, or other Robots).
Check robots for grease and/or excessive anti-static compound on any parts that might touch field tiles, elements, or walls.
Hot glue when used to secure cable connections.
Check for signs of hot glue used for other purposes. For example, teams may hot glue nuts inside the cavities of flex wheels used for flywheels as a work around to add weight without using the official flywheel weights.
An unlimited amount of non-elastic rope / string, no thicker than 1/4” (6.35mm).
Measure with calipers as needed. Note that for 2023-24 there is no minimum thickness for string.
Commercially available items used solely for bundling or wrapping of 2-wire, 3-wire, 4-wire, or V5 Smart Cables, and / or pneumatic tubing are allowed. These items must solely be used for the purposes of cable / tubing protection, organization, or management. This includes but is not limited to electrical tape, cable carrier, cable track, etc. It is up to inspectors to determine whether a component is serving a function beyond protecting and managing cables and tubing.
Some examples are shown below.
Non-functional 3D printed license plates, per <R12> and <R24>, are permitted. This includes any supporting structures whose sole purpose is to hold, mount, or display an official license plate.
Please note that plates must be pairs of red and blue and can only have white numbers and letters. See examples below.
Rubber bands that are identical in length and thickness to those included in the VEX V5 product line (#32, #64 and 117B).
#32 is 3”x1/8” when not stretched under load. #64 is 3-½”x1/4”. 117B is approx 7”in diameter. Rubber bands may come in different colors, and all colors are legal. Some legal examples are shown below.
Pneumatic components with identical SMC manufacturer part numbers to those listed on the VEX website.
View this article for an official list of legal pneumatic parts.
Zip ties that are identical in length and thickness to those included in the VEX V5 product line (4” or 11” long).
Examples of zip ties that don’t match those in the VEX product line:
Examples of Illegal Materials
The first image below is an industrial bearing not sold by VEX (violates rule <R11>).
The 2nd image is non-VEX anti-slip matting (black, but too large). Anti-slip matting must be black in color, and no single piece can exceed a size of 12”x15” per the VEX product listings.
5" Flex Wheels are not legal for use in VRC.
VEX 2.75in single-roller omni directional wheels (276-2165, shown in the 3rd image below) are considered legacy/discontinued products, and are not legal for use in VRC.
Rule R8: Decorations
Decorations are allowed. Teams may add non-functional decorations, provided that they do not affect Robot performance in any significant way or affect the outcome of the Match. These decorations must be in the spirit of the competition. Inspectors will have final say in what is considered “non-functional.” Unless otherwise specified below, non-functional decorations are governed by all standard Robot rules.
To be considered “non-functional,” any guards, decals, or other decorations must be backed by legal materials that provide the same functionality. For example, if a Robot has a giant decal that prevents Discs from falling out of the Robot, the decal must be backed by VEX material that would also prevent the Discs from falling out. A simple way to check this is to determine if removing the decoration would impact the performance of the Robot in any way.
Putting laminated or otherwise "hardened" images on pieces of non-skid, as (perhaps) shown in the very low-res image below, changes the behavior and functionality of the anti-skid matting that it is attached to and should NOT be allowed.
R8a: Anodizing and Painting
Anodizing and painting of parts is considered a legal nonfunctional decoration.
R8b: Small Cameras
Small cameras are permitted as non-functional decorations, provided that any transmitting functions or wireless communications are disabled. Unusually large cameras being used as ballast are not permitted.
R8c: VEX Electronics are NOT Decorations
VEX electronics may not be used as non-functional decorations
A team may not mount a 2nd VEX V5 brain, or any other electronic part in the VEX Robotics line of parts, as decoration.
R8d: Decorations Can’t Mimic Field Elements
Decorations that visually mimic Field Elements, or could otherwise interfere with an opponent’s Vision Sensor, are considered functional and are not permitted. The Inspector and Head Referee will make the final decision on whether a given decoration or mechanism violates this rule.
Any items that appear similar to current VEX field game elements will not be permitted as decorations (e.g., vision sensors for this season’s game may be looking for green/red/blue triballs and red and blue goals/match load zones).
R8e: Internal Power Sources
Internal power sources (e.g., for a small blinking light) are permitted, provided that no other rules are violated and this source only provides power to the non-functional decoration (i.e. does not directly or indirectly influence any functional portions of the Robot).
Power sources for decorations can’t affect the rest of the robot.
R8f & R8g: Decorations that Provide Feedback
Decorations which provide feedback to the Robot (e.g., by influencing legal sensors) would be considered “functional,” and are not permitted.
Decorations which provide visual feedback to Drive Team Members (e.g., decorative lighting) are permitted, provided that they do not violate any other rules and serve no other function (e.g., structural support).
Rule R12: Motor Limits
- Robots may use any combination of VEX V5 Smart Motors (11W) (276-4840) and V5 Smart Motors (5.5W) (276-4842), within the following criteria:
a. The combined power of all motors (11W & 5.5W) must not exceed 88W.
b. V5 Smart Motors, connected to Smart Ports, are the only motors that may be used with a V5
Robot Brain. The 3-wire ports may not be used to control motors of any kind.
Motor comparison images for (left to right) 11w V5 Smart Motor, 5.5w V5 Smart Motor, and legacy (not legal) EXP motor.
Rule R13: Battery Limits
Electrical power comes from VEX batteries only. Robots may use one (1) V5 Robot Battery (276-4811) to power the V5 Robot Brain.
No other sources of electrical power are permitted on the robot, unless used as part of a non-functional decoration per R8e. There are no legal power expanders for the V5 Robot Battery.
Rule R14: No Modifying Electronics or Pneumatics
No modifications to electronic or pneumatic components are allowed. Motors (including the internal PTC or V5 Smart Motor firmware), microcontrollers (including V5 Robot Brain firmware), cables, sensors, controllers, battery packs, reservoirs, solenoids, pneumatic cylinders, and any other electrical or pneumatics component of the VEX platform may NOT be altered from their original state in ANY way.
Teams may make the following modifications to the V5 Smart Motor’s user-serviceable features. This list is all-inclusive; no other modifications are permitted. Where applicable, the components listed below (in the specific applications listed below) are permissible exceptions to R11.
i. Removing the gear cartridge, or replacing the gear cartridge with other official cartridges.
ii. Removing or replacing the screws from the V5 Smart Motor Cap (276-6780).
iii. Removing or replacing the threaded mounting inserts (276-6781).
iv. Aesthetic / non-functional labeling (e.g. markers, stickers, etc).
V5 Smart Motors (11W) must use an official VEX V5 gear cartridge. For the purposes of this rule, the gear cartridges found within the V5 Smart Motor are considered “part of the motor.” Therefore, any physical or functional modifications to official gear cartridges is not permitted. 11w V5 Smart Motors may only use official VEX motor cartridges.
Custom cartridges for 11w Smart Motors (including 1:1 options that were legal for Spin Up) are no longer legal for use in competition.
For the purposes of this rule, the gear cartridges found within the V5 Smart Motor are considered “part of the motor”. Therefore, any physical or functional modifications to official gear cartridges is not permitted.
Illegal Motor inserts: Inside of a motor cartridge that was altered with zip ties.
Rule R18: Custom Plastic
A limited amount of custom plastic is allowed. Robots may use custom-made parts cut from certain types of non-shattering plastic. It must be possible to have cut all of the plastic parts on the Robot from a single 12” x 24” sheet, up to 0.070” thick.
Note that this rule’s limit on custom plastic refers to functional components only, and doesn’t include plastic used as legal decoration. Teams should be prepared to provide a ‘map’ of their functional plastic that shows that it could have been cut from a single sheet. Plastic may be a mix of types, and does not actually have to be cut from a single sheet.
The robots below could appear to have more plastic than is made legal by rule R9. Inspectors should check Plastic/Lexan maps against the actual functional robot parts. If in doubt, measurements should be double checked. When deciding whether a piece of plastic is functional or decoration, the most important thing to consider is whether removing it would change the way the robot interacts with other things in the game (e.g., does it act to keep discs from moving into or beneath the robot?). Inspectors have the final say on whether a piece of plastic counts against the limit or not.
Rule R20: Legal Non-VEX Fasteners
Certain non-VEX fasteners are allowed. Robots may use the following commercially available hardware:
#4, #6, #8, M3, M3.5, or M4 screws up to 2.5” (63.5mm) long.
Note that for 2023-24, rule R20a does not specify legal/illegal materials for screws.
Shoulder screws cannot have a shoulder length over 0.20” and a diameter over 0.176”.
Any commercially available nut, washer, standoff, and / or non-threaded spacer up to 2.5” (63.5mm) long which fits these screws.
The red box for rule R20 states that non-VEX fasteners shouldn't provide additional functionality beyond the standard parts, and that it is up to the Inspector (and through them, the Head Referee) to decide whether any specific part adds functionality.
The first image below shows a legal plastic standoff. The second shows a pair of 1" washers legally used as part of a robot's expansion mechanism.