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PROTO Socket: Metric, 3/8 in Drive Size, 21 mm Socket Size, 12-Point, Std, Chrome - 3/8" Drive Hand Sockets
PROTO3/8" Drive Hand Sockets

PROTO Socket: Metric, 3/8 in Drive Size, 21 mm Socket Size, 12-Point, Std, Chrome

The PROTO Socket: Metric (SKU J5221M, MPN J5221M) is a 3/8" Drive Hand Socket with a 21 mm, 12-point standard socket size. It is constructed from chrome, as specified by the manufacturer.

SKU 3G-OTH-319341

Brand
PROTO
Item
Socket: Metric, 3/8 in Drive Size, 21 mm Socket Size, 12-Point, Std, Chrome
Category
3/8" Drive Hand Sockets
Available to Order
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Local availability & support

Delivery
Worldwide DHL shipping from Singapore; 7–14 business days door-to-door for most destinations.
Payment
Invoicing in USD. Bank transfer (SWIFT) and corporate PO accepted.

Technical Specifications

PROTO
Manufacturer Part Number
J5221M
Type
12-Point, Std, Chrome, Socket
Socket Size
21 mm
Drive Size
3/8 in

Technical Documents

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PROTO Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The PROTO Socket: Metric (SKU J5221M, MPN J5221M) is a 3/8" Drive Hand Socket with a 21 mm, 12-point standard socket size. It is constructed from chrome, as specified by the manufacturer.

Frequently Asked Questions

What is the PROTO J5221M socket used for?

The PROTO J5221M 21 mm, 12-point socket is used for tightening or loosening metric fasteners with a 3/8 inch drive ratchet or torque wrench. It is commonly applied in automotive repair, industrial maintenance, and assembly tasks where precise torque and a secure fit on hex-head bolts or nuts are required.

What are the specifications of the PROTO J5221M socket?

The PROTO J5221M is a 3/8 inch drive hand socket with a 21 mm, 12-point standard socket size. It is made of chrome, as specified by the manufacturer. The socket is metric and designed for general-purpose fastening applications. The manufacturer part number is J5221M, and the SKU is 3G-OTH-319341.

Where to buy the PROTO J5221M socket worldwide?

You can source the PROTO J5221M socket worldwide through 3G Electric, a global industrial equipment distributor established in 1990. We handle full logistics, customs clearance, and delivery to your location. Contact us for availability and lead time; we supply this PROTO socket to customers across multiple industries.

How to select the correct PROTO socket size?

To select the correct PROTO socket, match the drive size (3/8 inch) to your ratchet or tool, and choose the socket size (21 mm) that fits the fastener head. For metric fasteners, use a 12-point socket like the J5221M for better engagement on hex bolts. Always verify the fastener type and torque requirements before use.

Used in

Common applications for PROTO
Automotive assembly — PROTO J72102 impact socket set for fastening lug nuts on production lines
Heavy equipment maintenance — PROTO J3772T flare nut wrench for hydraulic line fittings on excavators
General industrial repair — PROTO J795SA adjustable wrench set for tightening bolts on conveyor systems
Aerospace manufacturing — PROTO J5240A slotted bit socket for adjusting fasteners in confined spaces
Oil and gas pipeline work — PROTO J5438 12-point socket for valve assembly in refineries
Construction site toolkits — PROTO J8179-T500 double box wrench for structural steel bolting

PROTO Products

3G Electric supplies PROTO 3/8" drive hand sockets. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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Cross-referenced by specification & description
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PROTO Socket: Metric, 3/8 in Drive Size, 20 mm Socket Size, 6-Point, Std, Chrome, Not Tether Capable (MPN J5220MH)

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