The 3RH2131-2AN20: That gives the panel builder room to route wiring without fighting the orientation. These are the minimum air gaps to adjacent metalwork or other devices — ignore them and you risk flashover at pollution degree 3 (the industrial environment rating this part carries).
Switching capacity and endurance
Rated operational current is 10 A at both 24 V and 230 V, which covers most control-circuit loads — PLC outputs, relay coils, solenoid valves. The mechanical endurance is 30 million operating cycles, which for a contactor that sees a few cycles per minute in a conveyor or packaging line translates to years of service before the contacts wear. The contact configuration is 3 NO + 1 NC instantaneous contacts. That is a common layout for interlocking two contactors or for signalling back to a PLC that the main power contactor has picked up.
Relative humidity minimum is 10 %. The RoHS compliance date is 10 January 2009, meaning the part meets the EU directive for substances of concern. For a maintenance-spares purchaser, this covers the basic documentation requirements: the part carries the expected environmental compliance for industrial control gear.