I ordered the belts as backup. The belt has broken frequently. Twice it was my fault in that I caught the brush in the fringe of my oriental carpets. The last time it broke, I was just vacumning the rugs. I believe the belt doesn't exactly match the power of the unit....maybe some other reason.
Teeth larger than original belt causes excruciatingly loud whine from the Hayden Superpak powerhead. MD Customer Service has been very helpful - sent me a replacement pulled from a new Superpak. The replacement works perfectly.
the belt breaks too easily and too quickly if something gets tangled in the electric brush. (NOTE: The belt is made extremely well. The issue is this is a product from the 70's, used under many brands, and doesn't have the technology of the Stealth or EdgeLift which turn off before the belt breaks. If you want to upgrade to the newer brushes you will have to buy a complete attachment kit here www.builtinvacuum.com/electricpowered.html since the hose with this older brush is not compatible with the new electric brushes.)
The belts, in addition to being quite expensive seem to break much easier than the stock belts. If I accidentally suck the corner of a throw rug, the belt immediately breaks. This wasn't an issue with the original belts - the motor would just stall. (MD NOTES: These are the manufacturer's original belts and under warranty, especially if breaking in batches and quickly.)