The SQM200-1222 is a magnetic floating switch by Misc. It is designed to detect liquid levels in tanks, canisters, and other liquid-filled containers. It works by measuring the effects of a magnetic field created by a small magnet inside the switch. When the switch is submerged in liquid, the magnet creates a disturbance in the field, which triggers a signal to activate the switch. The SQM200-1222 has a sensing range of up to 20mm, and is rated at IP68 for water resistance and durability.