Impact drivers are high-torque tools primarily used for driving screws and tightening nuts.  These tools are lighter and smaller than drill drivers, and although they are not as versatile, they will perform many of the same functions. Since their torque output is higher than a typical drill driver, they get through work more quickly.  Ideal for jobs such as laying subfloors, building decking, or simply projects that require you to be driving hundreds of large screws. Impact wrenches are essentially the same machine but typically more heavy duty and have square drives for attaching sockets. Drivers are available in various power sources including electric corded at 110V and 220V and cordless with Li-ion, Red Lithium or Procore batteries of various voltages including 12V, 18V,36V and 54V and various Ah ratings including  2.5Ah, 4Ah, 5Ah, 6Ah, 8Ah, 9Ah and 12Ah.  Cordless products are also available as body only or bare unit, in purchasing a bare unit the cost is reduced due to the exclusion of batteries and chargers.