The 3RT2018-2LF42-0LA0 is a Siemens SIRIUS power contactor in the S00 frame — the smallest in the family, at 45 mm wide and 121 mm deep. The 110 V DC coil uses spring-type terminals, so no screwdriver needed for the magnet wire — just strip and push.
The DC coil pulls in at 110 V nominal, with a pickup threshold of 0.7 × rated value — so it'll hold in down to about 77 V. Dropout time is 7 to 20 ms on DC, arcing time 10 to 15 ms. That's fast enough for most motor start/stop circuits but not for safety-rated instant-off; if you need that, pair it with a separate safety relay. For motor loads, the contactor carries 14 A at 480 V — that's a 7.5 hp motor at 480 V three-phase, typical for a small conveyor or pump. At 24 V DC on the auxiliary side, it switches 10 A, which covers most PLC output cards and indicator loads.
Clearance and mounting position
That helps when you're squeezing it into a tight gland plate area.