Friction wedge-belts are an early solution that solved the slippage and alignment problem. The shape of the belt tracks in a mating groove in the vee pulley (or sheave), with the result that the belt cannot slip off. The belt also tends to wedge into the groove as the load increases, the greater the load, the greater the wedging action, improving torque transmission and making the vee belt an effective solution. Wedge belts transmit more power than a typical V-belt with a comparable top width. These belts have a space saving shape that delivers high performance and efficiency. Wedge belts can decrease the number of belts required and reduce pulley size. The belts have a specially treated jacket to give superior anti-static, heat and oil resistant properties.