Impact sockets are designed for use with powered impact wrenches or ‘drivers’, as they are sometimes called. Impact wrenches can be powered pneumatically (by compressed air), electrically, or hydraulically (oil).
The combination of an impact wrench and impact socket can deliver greater torque to the head of a fastener than can be achieved with a manual wrench.
Impact sockets are a different colour to other sockets, due to the black oxide coating (also called ‘industrial surface finish’), that is applied to them. Black oxide is used as a surface finish on impact sockets to protect against corrosion, as chrome plating would chip and flake off, due to the vibration caused by a powered impact driver.
The drive socket end of larger impact sockets has a grooved ring around the outside. This enables a locking pin and retaining ring to be used.