This part is a kind of semiconductor called HJR-21FF.

Function of this product has TCB Relay.

Manufacturers : TBO

Image and pinout :

Some of the text within the PDF file :

www.DataSheet.co.kr E L E C T R O N I C S T810S-P002C PCB 继 电 器 ● 12A switching capability ● SPST-NO configuration ● Small footptint ● Sealed version available ● Class B/F available ● Conform to RoHS,ELV directive 20.3×16.8×20.3 HJR-21FF 03001003710 c u s E173485 R50031008 ■ORDERING CODE 定购代码 HJR-21FF 12VDC S H 1 1. 2. 3. 2 3 4 Relay Model 继电器型号 Coil Nominal Voltage 线圈额定电压 3,5,6,9,12,18,24,48VDC S: Sealed 密封 （TBF-1） 5 4. 触点转换形式 H: Form A Z: Form C 5. Insulated Level 绝缘等级 TBF-1: Class F 级 Nil: Standard Type 标准 ■COIL DATA 线圈参数（at 20℃） Nominal Voltage额定电压(VDC) Coil Resistance线圈阻值(Ω±10%) Rated Current额定电流(mA) Max Operate Voltage 最大吸合电压( [ ... ]

HJR-21FF PDF Datasheet Download