It"s delay turn-on module.Module Properties: NE555 chipDimension: 77 (L) * 23 (W) * 18 (H) mm (with potentiometer)Input voltage: DC12VAdjustable time: 0 to 10secControl voltage: AC 0~250V / max. 10A, DC 0~30V / max. 10AMax. loading: 2200W Delay modue:delay connect module One size: 77mmX23mm X 18mm length X width X height the operating voltage: 12 volts DC; (otherwise 5V optional) the use of high-performance timing CPU design. the power indicator LED and switch trigger timing indication LEDs; the output can be connected to AC 250V 10A DC 30V 10A load; there is the chronopotentiometry regulation time, adjustable from 0 to 10 seconds by default, or by changing the capacitance adjustment time longer.Often used in：Vehicle equipment-delay to prevent car ignitionWhen the current is too large burnt vehicle device.Chip (NE555) Characteristic: Timing from Microseconds to HOURS Simple Circuitry Precision Pulse Generation / Timing, FMAX = 500 KHz Package: 8 pin DIP Use a single 4? to 16 VDC supply Excellent temperature stability 0.005% / °C Adjustable Duty Cycle Monostable or Astable Operation Countless Application and Information Sources