Proto J5421MH 21mm 6-point 1/2 in Drive Hand Socket

Product Description

The PROTO J5421MH is a 21 mm, 6-point hand socket designed for use with a 1/2 inch drive ratchet or breaker bar. Built from alloy steel with a chrome-plated finish, this socket delivers the corrosion resistance and surface hardness that professional mechanics and maintenance technicians expect in daily shop use. At 1.5 inches in overall length, it is a standard-length socket suited for fastener access in typical clearance situations. It meets ASME B107.5 standards, confirming dimensional and strength compliance for hand socket tools.

This socket is a standard choice for automotive, fleet maintenance, and industrial applications where 21 mm fasteners are common. The 6-point design concentrates drive force on the flats of the fastener rather than the corners, reducing the risk of rounding under high torque. It is appropriate for use in professional shop environments, field service trucks, and maintenance facilities. The 1/2 inch drive size makes it compatible with a wide range of common ratchets, extensions, and torque wrenches in that drive family.

Key Features

• 21 mm socket size fits standard metric fasteners common in automotive and industrial work
• 6-point geometry drives on fastener flats, reducing corner rounding under load
• 1/2 inch drive compatible with standard ratchets, extensions, and torque wrenches
• Alloy steel construction with chrome-plated finish for corrosion resistance and durability
• Standard length at 1.5 inches overall for general-clearance fastener access
• Meets ASME B107.5 dimensional and performance standards for hand sockets

Compatibility

Designed as a standard 1/2 inch drive, 21 mm hand socket for use with any 1/2 inch drive ratchet, breaker bar, extension, or torque wrench conforming to standard drive dimensions.

Installation Notes

Install and remove by a qualified mechanic or maintenance technician using standard 1/2 inch drive tooling. Confirm the socket is fully seated on the fastener before applying torque to avoid slippage. Do not use hand sockets with impact drivers unless the socket is rated for impact use. Inspect the socket for cracks or deformation before each use and remove from service if damaged.