Billet Piston Stopper 10mm and Mod to 14mm

Dave's had these Nice stoppers last week for $3.99, so I bought 2. They have the 10mm spark plug thread. One I am making a sleeve with a 10mm x 1.0 female thread and a 14mm x 1.25 male thread. Thread it on the 10mm stopper and use it in your stock Cag and C1, Polini 14mm spark plugs.