It is a great pleasure to have this affordable Lisle instrument! Compressing a spring is always a critical operation, as a large amount of potential energy, if released unexpectedly, can be deadly. I appreciate the way the U-bolts grip the coil spring as an added safety measure. Follow the manufacturer's instructions and liberally grease the threads. This is one of the instruments I have insisted on being made in the USA as inconsistent Chinese quality can lead to disaster.