These stainless steel replacement retaining rings are made to fit 0.75 in. (internal) diameter Swift-Seal Compression Port Adapters with flange sizes KF-16 (P103920), KF-25 (P103770), and KF-50 (P103779).Compression ports are typically used to make quick connections to tubes and half nipples, commonly found on gauges, instruments, and gas supply lines. These are Axially Assembled Internal retaining rings made act as a stop when properly installed within a Swift Seal fitting. Avoid scratching the bore interior by using correctly sized Ring Pliers.