I took SScnc's idea and found a belt at the local auto parts store that yields four belts from one. The Gate belt part number K040275 / 4PK702, is a micro-V, "serpentine" belt with three grooves. The belt is 717mm (28.5") circumference. If you take a new razor blade and use the belt groove as a guide, you can accurately slice four useable belts:



Each belt is very close the 5M710.