Automotive flashers are OEM replacements for most applications. Flashers come in either thermal type, or electromechanical type. A thermal flasher uses a basic bi-metallic element that heats up and cools down rapidly as the load for the lamps passes through the flasher. This controls the flash rate, or speed of the flashing circuit. With this type of flasher, the more lamps you have on your circuit, the faster the flash rate will be. Electromechanical flashers have a built-in timer circuit and relay, so that no matter how many lamps you have on your circuit, the flasher will operate at the same flash rate. This type of flasher is suitable for maintaining a steady flash rate when towing a trailer, for example. 2 pin flashers have an 'X' terminal for power input, and an 'L' terminal for the flasher output. 3 pin flashers have an additional terminal labeled 'P' for the pilot light indicator.