Relevant rules: R7 j : A comprehensive list of legal parts can be found in the VEX IQ Challenge Legal Parts Appendix, at https://www.vexrobotics.com/iq/competition/viqc-current-game . This Appendix is updated as needed if / when new VEX IQ parts are released, and may not coincide with the scheduled Game Manual updates in G20.
R8 : Non-VEX IQ components. Robots are allowed to use the following additional “non-VEX IQ” components: b : Rubber bands that are identical in length and thickness to those included in the VEX IQ product line (#32 & #64).
The following document has all the legal parts for VEX IQ: https://content.vexrobotics.com/docs/21-22/pitching-in/LegalParts.pdf
There are rubber bands available in the legal parts appendix that aren't #32 or #64. 228-2500-470 Silicone Rubber Band #117B 228-2500-1225 2x30 mm Square Silicone Belt
If teams want to use these on their robot, would they need to source them from kits or could they buy them from other sources as long as they are the same size?