Ferrules have different through-channel diameters and are used for adjustment of an injection rail (injector) capacity to motor cubic one. It can be also used for other joints with 3/8” thread, where reduction to 1/8” thread is required.
Ferrules are made of brass. Sealing O-ring is made of rubber resisting LPG or oil aggression within full range of injection rail working temperatures.
specification format pdf - download