This Allen key socket fits onto the 1/2 inch drive of a hand ratchet. When attached the allen key socket can be used to tighten or loosen any bolts or fitting that have an 8mm hex-shaped inner. Examples of this would be a socket cap screw or a key clamp fitting that has a grub screw for tightening the fitting to a tube handrail. These types of allen key sockets are not suitable for air driven tools. Can only be used with hand tools such as small breaker bars and ratchets.