The main advantage of steel banjo bolt fittings is in high-pressure applications. The name stems from the shape of the fitting, having a large circular section connected to a thinner pipe, generally similar to the shape of a banjo.

A hydraulic banjo adaptor fitting comprises of a perforated hollow bolt and spherical union for fluid transfer. Commonly found in automotive fuel, motor oil and hydraulic systems.

Compared to pipe fittings that are threaded, banjo fittings have the advantage that they do not have to be rotated relative to the mating fitting.  This avoids risk of damage by twisting the hose when screwing the fitting into place.