Double-V (Hexagonal) Classical Belts - AA, BB, CC Cross Sections Specially designed for serpentine and reversing drives, Double V-belts transmit power from both sides of the belt. Polyester cords and cotton/polyester cover provide maximum strength and length stability with minimum stretch. These belts conform to ARPM Engineering Standard IP-21. Double V-belts are available in three standard ARPM sections - AA, BB and CC - and in lengths up to 540 inches. They are specified by belt section letters and a Standard Length Designation that is equivalent to the length of single "V" profile belts - Example: BB49