To install SW hacker replacement blades-insert blades into the slot of the ferrule (the arrow head). Secure in place with the setscrew. Ensure that the blades rotate freely from open to closed. Install shrink tubing by placing a single band over the tip with the blades fully enclosed in the slot. Slide the band down the ferrule until it is in the slot. Slide the band down the ferrule until it is in the retaining groove. The blades may move slightly. If the band does not stay in the retaining groove, use a heat source such as a pocket lighter or a hair dryer to shrink the band down. Care should be taken to not overheat the band. CAUTION: This product is EXTREMELY sharp. Serious injury can occur if handled improperly. Please follow the instructions carefully.