Description: 1. Acme threaded rod with broad spring contact and built-in detent pins to lock the coil spring in place for safer spring compression;2. Acme threaded rod allows for durable and smooth compression of springs both on or off the vehicle with hand or power tools3. Constructed with forged hooks and center screw hardened for maximum strength and longevity.4. Using a 3/4″or 19mm socket and ratchet turn the main shaft compressing the strut spring enough to safely remove the fastener nut holding the cartridge Application: Designed to withstand extreme pressure in any environment, ideal for professional mechanic and automotive repair novice.Instructions: 1. lubricate both main shafts with oil.2. Align the hooks with the safety pins backed off so the hooks will fit over the spring3. Position both set of hooks 180° a part, opposite each other.4. Push safety pins in the lock position on hooks.5. Using a 3/4″or 19mm socket and ratchet turn the main shaft compressing the strut spring enough to safely remove the fastener nut holding the cartridge Note: 1. The color of blow case may be varied, you may receive item with black or red carry case, it won’t affect item function. 2. DO NOT USE IMPACT DRIVER! Caution： A compressed spring can inflict bodily injure, always wear safety glasses and gloves