Function – This item is made from premium material for durable and long-lasting use. The GT2 series of belts are designed specifically for linear handling. Use a rounded profile of the teeth which ensures that the belt tooth fits smoothly and with precision in the groove of the pulley, so when it reverses direction of pulley belt, there is no place to move into the groove Designed specifically for linear handling; for optimal performance we want at least 6 contact with the pulley teeth at a given time. The strap which minimizes the chance of slippage and helps reduce the recoil further. In practice this means that it wishes a minimum of a pulley 12 teeth, and usually I am trying to get at least 32 teeth. GT2 belts and compatible pulleys (GT2 Pulley) are popular choices for Reprap saw and RepStraps. Size: about 5 * 3 * 0.8 cm/2 x 1.2 x 0.31 inches (L * W * H); Material: Aluminium Package – GT2 Aluminum Timing Pulley x 5; Screws x 10; Allen key x 1