The Siemens 3RH1 244-1BB40 is a SIRIUS auxiliary contactor relay — a 24 V DC coil switching 4 normally open and 4 normally closed auxiliary contacts, rated for 6 A at up to 690 V insulation voltage per IEC 60947-5-1. That 4NO+4NC contact arrangement means it can handle both signal interlocking and load-side feedback in one package, typical for building out a motor starter's control circuit or extending the I/O of a power contactor in a panel.
Where it lives in the panel
Size S00 footprint — 45 mm wide, 111 mm deep, 57.5 mm tall — screws or snaps onto 35 mm DIN rail per DIN EN 50022. Side-by-side mounting with zero gap is fine; no derating needed for adjacent units at rated current. The screw terminals accept 2x (0.5…1.5 mm²), 2x (0.75…2.5 mm²), or 2x 4 mm² solid/stranded, and 2x AWG 20…16 or 18…14 for the auxiliary circuit. Strip length 8 mm — standard for the SIRIUS family.