extremely useful tool when applying sealant as it will enable an accurate application when filling gaps and sealing joints to provide a watertight strong bond. To use the gun: 1. Press the release trigger at the back of the gun and pull the plunger back 2. Place the cartridge into the gun pointing the nozzle towards the front of the gun. 3. Push the plunger back into place. 4. Cut a hole in the tip of the tube to allow the sealant to feed through. 5. Hold the gun along the gap at a 45 degree angle and squeeze the trigger to begin sealing.