T21 Turbine Brush belt is no longer available. It was a cogged belt 5/16" wide, 6-3/16" long when flattened, and the distance between cog peaks is 1/8". We recommend replacing the obsolete T21 vacuum cleaner head with the TurboCat Vacuum Brush which is a direct replacement to the T21. The TurboCat has a much lower profile allowing it to get under more furniture. Additionally, if you have wall-to-wall carpet we highly recommend replacing your T21, hose, and tools with a brand new Electric Attachment Kit, which will fit your vacuum system without any modifications and groom your carpets better than ever - compared to the air-driven vacuum head. Learn how your system works with an Electric Vacuum Kit.