TEKTON 14153 3/8-Inch Drive by 21 mm Shallow Socket, Cr-V, 6-Point 6-point opening snugly fits hex-shaped fastener heads to apply maximum torque without slipping Advanced design grips flat sides of fastener heads, not corners, to prevent round off Shallow well and slim walls allow socket to fit into tight, narrow spaces Detent notches in drive end lock onto ratchets and extensions Made from premium chrome vanadium steel with a durable mirror chrome plated finish