ACHE (air cooled heat exchanger) belts have a special "Z" twist construction designed specifically for air cooled heat exchangers. Because the ACHE drive has a vertical shaft, the ACHE belt is built with "Z" twist cords only. This gives the belt an upward direction of lateral movement which reduces excessive wear on the bottom side of the belt. The energy efficient ACHE synchronous belt performs at 98% operating efficiency for reduced energy consumption. Timken Belts Synchronous Drive Belt, Air-Cooled Heat Exchanger Z-Twist Cord, 14 mm Pitch, 2800 mm Overall Length, 40 mm Width, RPP Tooth Profile, Rubber, Non-Aramid Fiber Reinforced