Snap-on’s QD series click type torque instruments, Nos. QD2R100 and QD3R250, feature a certificate of calibration, with actual certification readings and instrument serial numbers. The minimal friction “hour glass” cam retains and releases lubricant where needed to reduce friction. These torque wrenches are accurate to +/- 4 percent clockwise and +/- 6 percent counterclockwise from 20 percent to 100 percent full scale. With a positive stop, the instrument cannot be accidentally disassembled if wound down past scale. Storage case included.