The Siemens 3RQ4901-0A is a 2-pole connecting comb for the SIRIUS 3RQ4 coupling relay family's narrow design. It bridges identical potentials across adjacent relay positions in a DIN-rail terminal block arrangement, with a maximum infeed current of 10 A. This keeps the wiring tidy and reduces the number of jumpers needed when multiple coupling relays share a common supply rail.
The comb snaps onto the relay terminals to create a common potential bus. Two poles means it bridges both the A1/A2 coil supply and the contact common, depending on the wiring scheme. Keep the infeed point to one end and stay under the 10 A limit across the whole daisy chain — the comb itself is the current-carrying path, not a busbar.