Proto J4990-9MST Hand Hex Bit Socket 3/8 in Drive 9 Mm

Product Description

The PROTO J4990-9MST is a hand hex bit socket designed for 3/8 inch drive ratchets and extensions. It accepts a 9 mm hex bit and delivers reliable torque transfer in tight or recessed fastener applications. With an overall length of 1-49/64 inches and a bit length of 3/4 inches, this socket is sized for controlled, precise work on hex-head fasteners encountered in mechanical, electrical, and HVAC service. It weighs 0.11 pounds, making it a lightweight addition to any service kit. Technicians across plumbing, electrical, and mechanical trades keep hex bit sockets like this one on hand for panel fasteners, setscrew fittings, and equipment access hardware.

This socket suits residential and light commercial service work where 3/8 inch drive tooling is standard. It is well suited for HVAC equipment service, electrical panel work, and plumbing fixture installation where 9 mm hex fasteners are common. The compact overall length allows use in moderately confined spaces without sacrificing drive engagement. It is sold individually and fits standard 3/8 inch drive tool sets.

Key Features

• 3/8 inch drive compatibility fits standard ratchets, extensions, and torque wrenches
• 9 mm hex bit size for metric hex-head fasteners
• Bit length of 3/4 inches provides solid engagement depth
• Overall length of 1-49/64 inches for use in moderately confined areas
• Lightweight at 0.11 pounds for reduced hand fatigue during extended service

Compatibility

Designed as a standard 3/8 inch drive hex bit socket compatible with 3/8 inch drive ratchets, extensions, and torque wrenches that accept square-drive accessories.

Installation Notes

This socket is installed and used by service technicians across HVAC, plumbing, electrical, and mechanical trades. Always ensure the drive connection is fully seated before applying torque to avoid slippage or fastener damage. Inspect the bit tip for wear before use, as a worn hex profile can round fastener heads. No power tools should be used with hand-rated sockets unless the socket is rated for impact use.