Stahwille's 703N series torque wrenches have been in service with the US military for over 3 1/2 years. They currently hold 1-year calibration cycles with the USAF (33K-1-100-1). They feature interchangeable heads and a 5-year accuracy warranty to the military and a limited lifetime warranty. The 703N torque wrenches use no springs, which makes zeroing unnecessary and allows you to use the entire range of the wrench. They will suffer no damage if used as a breaker bar or if dropped. A set of Stahlwille wrenches is up to 10 pounds lighter than other sets. For more information visit www.stahlwilletools.com or call (800) 695-2714.