The docking alarm sounds when the anchor is close to docking. It works with rope/chain or all-chain rode. Plug and Play cables. It installs up to 2 units. It includes: 1 10x8-mm magnet and motor sensor for rope/chain installations.Includes: 1 magnet 10 x 8 mm; sensor to be applied to the motor for rope/chain winches. Protection grade IP65