The HTD tooth profile adds sturdiness to the belt resulting in an increased torque transmission capability and a reduction in transmission noise, an increase in tooth jump resistance, an increase in power transmitted and an increase resistance to tooth shear. Part numbers are identified by a 3 or 4 digit number e.g. 960 represents the pitch length in mm, a number and letter e.g. 8M the belts pitch and a 2 or 3 digit number e.g. 30 the belts width e.g. 960-8M-30.