B?? The B stands for a ?B? section v-belt.? This is considered a ?Classic? v-belt style that has a top width of 21/32 (0.656) inches, but is commonly referred to as a 5/8 (0.625) inch belt. The thickness of the belt is 13/32 (0.406) inches.
33? 33 inches is the inside circumference of the belt.? For B-section v-belts, the outside circumference is found by adding 3 inches to the inside length of the belt.? So, the outside circumference of the B33 belt is 36 inches (33+3).