These adjustable tap sockets are designed to be used with a 3/8" drive hand ratchet, socket wrench or extension bar. The jaws can be easily adjusted and have a knurled ring for extra grip when tightening. The adjustable design makes it suitable for other tools with a square shank, such as reamers and screw extractors. Fits taps with shank sizes up to 10mm. Ideal for tapping and reaming in tight spaces. Manufactured from tough HRC 38-45 steel with a Chrome Molybdenum steel body for added durability and longevity.