Belt broke on Rebel 17 and Ive seen several posts about replacements that will last should be an O ring not the fragile belt from Rebel. But none of them list a number or size to base a replacement on. The belt has a thickness of .177 or the same thing in foreign is 4.5 MM, and a diameter of 4.5 inches or 114.5 MM. I do not speak O ring and do not know what to look for or the best material for it to be made of so it will last a long time. The orange belts they come with are way too fragile and the company knows so they them in a 3 pack. This is getting serious as my vibratory is getting a new motor at Dillon, soon I will be bribing the kids in the neighborhood to spin them on 0000 steel wool.