The 3RH2911-1HA20-ZX95: Rated for a maximum of 10 A, but the real selection driver is the switching capacity at your control voltage. At 24 V the contacts handle 10 A (resistive) and 6 A (AC-15 inductive); at 230 V that drops to 6 A resistive and 1 A inductive. For 400 V control circuits the inductive rating is 3 A.
Snap-on mounting to the contactor or relay front — no DIN rail footprint of its own. The block measures 36 mm wide by 37.5 mm high by 43.7 mm deep, so it adds about 44 mm to the device depth. Wiring accepts 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with ferrule, or 2x (20 to 16) and 2x (18 to 14) AWG.