Siemens Direct-On-Line (DOL) motor starter 3RK1308-0AC00-0CP0 ET 200SP family
It is used to directly start 3-phase motors, with adjustable overload settings. Compact module for ET 200SP base units. Adjustable overload current: 0.9 … 3 A. Photos will show the part number, front / rear, and markings.