|Heavy duty polyurethane belts are the factory replacements for your Kreitler rollers. 1/4 x 72 inch is for most 4.5 inch drums (with 2 belt grooves) manufactured within the last 20 years. 1/4 x 66 inch is for 3.0 and 2.25 inch drums. Older Kreitler models (with 1 belt groove) use the 3/16 x 70 inch model, but call us to verify. The 3/16 will also fit many other brands, so take a measurement to be sure.