Boxend

A box-end wrench, often called a box wrench, is a hand tool used to turn fasteners. It has a closed, circular or oval ring that surrounds the head of a bolt or nut, providing contact on all sides. This design helps prevent rounding and allows higher torque transfer than an open-end wrench.

The interior of a box-end wrench is typically designed as a 6-point (hex) or 12-point (double-hex) configuration. Six-point box ends are common for hex nuts and bolts, while 12-point variants can engage a wider range of fastener heads and are sometimes used where clearance is limited. Boxes ends are usually forged from high-strength steel and finished with chrome plating or other corrosion-resistant coatings.

Box-end wrenches are preferred in situations that require greater grip and torque, especially when fasteners are stubborn or prone to slipping. They are also advantageous in confined spaces where turning a fastener with an open end is difficult, though they require sufficient room for the ring to clear surrounding material. Variants include offset, flex-head, and ratcheting box-end wrenches. Ratcheting versions incorporate a mechanism inside the ring to allow continuous turning with minimal repositioning, while offset and flex-head designs improve access around obstacles.

Historically, box-end wrenches emerged as part of the development of standardized hand tools in the early 20th century and became a staple in automotive, mechanical, and industrial work. They are commonly sold as individual tools or as sets covering a range of sizes. Proper use involves selecting the correct size to avoid rounding and applying torque within the tool’s design limits.