UA type is the most widely applied for single-acting or double-acting circuits. UB is the real Universal central manifold since, in addition to UA-type features, there are two extra lateral cavities to mount, for example, an integrated emergency hand pump and an externally adjustable flow control can be integrated in a UB manifold. U4 is recommended for compact and cost-effective double-acting circuits with a single cylinder, while UR is for bidirectional pumps.