To Use - Remove valve cover on your S.T. Dupont lighter. Screw refill into the filling valve of the lighter (you may hear a hissing sound as you do, this is normal). Position lighter and canister upside down and add a small amount of pressure. Wait 5 seconds. Remove refill and wait a couple seconds. Screw refill back into filling valve and position upside down again for 5 seconds. Remove refill and replace valve cover.