577-3426 Features: -Unique arc design increases surface contact by 400%. -Tappet style wrench for use on jam nuts and in confined areas. -Opening Type: Open/Open. -Head Angle: 15° Open Side. Use: -Open End Wrench. Size: -1/2"/9/16". Quantity: -Single. Measurement Type: -SAE. Product Type: -Wrenches. Generic Dimensions: -Overall Length: 10 in. Dimensions: Overall Product Weight: -0.17 Pounds.
From the Manufacturer
Stanley Proto Open End Wrenches include the patented Anti-Slip Design (ASD) which has a locking groove to help prevent the wrench from slipping off of the fastener, reducing the chance of hurt knuckles. The ASD also has an arched surface that spreads the turning force over a contact area larger than a conventional wrench.