SPST 12V 750/100A Grounded Intermtnt Solenoid (1 Per Quantity) Solenoids are a current carrying coil of wire wrapped around an iron core that when energized creates a magnetic field which produces a high current and force. Similar to a relay but unlike regular relays solenoids are used for heavy-duty applications like a motor on-off control. Solenoids are advantageous because they allow for a low input while generating a larger output as in the case of a starter solenoid. Rated for 12V DC.