This wrench is used to hold a fastener in place.

• A. Backup wrench
• B. Open-end wrench
• C. Box-end wrench
• D. Adjustable wrench

Answer: (A)

When you tighten a fastener with a wrench, you sometimes need a second wrench to keep the fastener from turning. That second tool, placed on the opposite side of the fastener, holds it steady while the primary wrench or torque tool applies torque. This backup wrench resists the reaction torque, preventing rounding or slipping and protecting both the fastener and the tools.

Other wrenches are meant to turn fasteners themselves rather than stabilize the opposite side. An open-end wrench and a box-end wrench are used to turn the nut or bolt. An adjustable wrench is versatile for gripping various sizes but isn’t specifically intended to back up and hold the fastener during tightening.