The Siemens SIRIUS 3RT2028-1AF04 is a size S0 power contactor rated 34 A at 480 V in AC-3 duty — the motor-switching current that governs real-world sizing for a 3-phase induction motor up to roughly that load. The AC-3 rating of 750 operating cycles per hour means it handles frequent starts and stops on a conveyor or pump without overheating the contacts.
Depth of 141 mm means it sticks out about 5.5 inches from the rail; make sure your gland plate or enclosure door clears that.
For the coil, the same screw terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²). Strip length for the main contacts is 16 to 8 mm. The coil draws 0.25 A at 50 Hz — a standard 24 VDC supply can drive it, but verify the inrush at pickup doesn't sag your control transformer.