Special tips:The color of blow case may be varied, you may receive item with black or red carry case, it won't affect item function. DO NOT USE IMPACT DRIVER! Caution: A compressed spring can inflict bodily injure, always wear safety glasses and gloves; 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 spring; 3. 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.