This seal-a-tube is colour coded and is available in 2 sizes, this is the narrow version which fits standard nozzles. Ensure that the inner pin inserts into the tube to create an airtight seal. When you are ready to use your silicone or caulk again, you just remove the seal-a-tube and you're ready to go. If any dried residue remains on the inner pin then this should be cleared off before you reuse it.