The 3RA2815-1FW10 is a Time Delay Contacts unit manufactured by Siemens. It is available in four sizes, S0, S00, S2, and S3, and features screw terminals for electrical connections. This unit is typically used for applications that require accurate timing and reliable control of switch contacts, including such applications as lighting, heating, and ventilation controls. The time delay contacts of the 3RA2815-1FW10 provide smooth transitions and exact start and stop times without any need for an external control system.