They are manufactured to perform at identical or higher levels than all major US Manufacturerâs belts of the same type. 2000mm Outside Length, 310 2/5mm Top Width, 20 Ribs DURA-PRIME BAND METRIC belts give superior belt performance proven through thousands of hours of customer use to be durable and dependable. The helically wound tensile cords are specially manufactured with, twisted, heat and chemically set, polyester material..