If you find your lighter running low on fuel, these specially designed butane tanks are just the thing you are looking for!
In order to use Butane properly - 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.
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.