Modern bikes are made of modern materials and a result of squeezing out every bit of performance from those bikes and materials is the necessity of a torque wrench. It's easy to over-do it and crack a frame or handlebar and very few of us have hands calibrated properly. It's recommended NOT to use this to loosen bolts or tighten left-hand threads.
Yearly calibration is recommended. We can help arrange that, contact us for more info.
Item 615485 has a 1/4" square drive while item 618486 has a 3/8" square drive.