The dome rests on an octagonal base and a new compression ring was installed after 2004.

A common improvement is an inner compression ring.

A compression ring allows for higher flange compression while preventing gasket failure.

The effects of a compression ring are minimal and generally are just used when the standard design experiences a high rate of failure.

Flared connectors lack a compression ring, but do use a threaded nut.

The pistons were of aluminium alloy, with three compression rings and one scraper ring.

The cylinder does not wear above the highest point reached by the top compression ring of the piston, which can result in a detectable ridge.

The RC30 had used a piston with one compression ring and oil control ring to reduce friction.

These pistons have three compression rings and two oil-control rings.

If the riser has been in place for a long time, it's possible that compression ring may not reseat properly.