Facom Digital Torque Angle Adapter (E.406) - digitally measures angles accurately and maintains calibration to +/-2% . For use with a standard 1/2" drive ratchet when tightening engine fasteners to torque angle specs (typically "stretch bolts" on cylinder heads...common with BMW and others). Locking keys prevent accidental change during tightening operations with LED's and buzzer for both visual and audio indication.

Features include.......

• Digital angle value readout
• +/-2° accuracy ( rotating 90° at speed of 30°/sec)
• Clockwise and Counter-clockwise operation
• Buzzer and LED indicator for the 9 pre-settable target torques
• 50 data memory for recall and joint torque auditing
• Auto Sleep after about 2 minutes idle
• Both AAA and rechargeable batteries are compatible

Here's the USAG video showing how to use the tool. The Facom E.406 and USAG 831A are the same tool.