The Siemens 3RQ4901-0B is a 4-pole connecting comb from the SIRIUS 3RQ4 family of narrow coupling relays. It bridges identical potentials across adjacent relay sockets in a control panel, with an infeed current-carrying capacity of max 10 A. This is the part that lets you daisy-chain common supply rails without point-to-point wiring.
Integration notes
Packaged singly, dimensions 95 x 93 x 65 mm. Snaps onto the DIN rail alongside the 3RQ4 relay base; the comb bridges the supply terminals without additional jumpers. Verify the infeed point — the 10 A limit is at the feed-in, not per pole.