Replace worn one-piece bakelite boiler cap-knob with a machined stainless steel threaded base with attached bakelite knob.

Replace worn one-piece bakelite boiler cap-knob with a machined stainless steel threaded base ready for a custom wooden or other top piece. Post threads are M12 x 1.75. Post height is 19mm.

Machined from solid stainless steel or brass and made in USA.

Adapter thread size differs depending on production date. Most Pre-millennium models use 12mm adapters; most post-millennium models use 11mm adapters. It is difficult to date models with certainty because parts may have been changed.

Therefore, we ask that buyers of adapters and adapter sets always measure the widest part of the sight tube cap's threads with a decent micrometer to prevent returns and resending. Postal fees can add up quickly. If you don't have a micrometer, bicycle, auto and motorcycle shops do.

Chrome bezel with black back.