All belts are certified to be within .020 of OEM required manufacturing specs. Most replacement belts can have up to 1/2in. variance in length. Longer belts affect the operation of the clutches and create inconsistencies in shifting. This also can cause excessive wear on the clutches. Top Cog construction that strengthens side wall Product Description All belts are certified to be within .020 of OEM required manufacturing specs.. Most replacement belts can have up to 1/2in. variance in length.. Longer belts affect the operation of the clutches and create inconsistencies in shifting.. This also can cause excessive wear on the clutches.. Top Cog construction that strengthens side wall. All belts meet or exceed OEM specifications. All ETI belts are made in the USA. Reference size 669x18x30. Fits Chinese Gy6