The "underwater connector on coil wire" option allows the standard 7.5" coil to be detached from the detector's electronics housing so any of the optional coils can be attached.

The optional coils greatly increase the versatility and enhance the capabilities of these detectors. For instance, there are two coils designed for boat deployment. Sit in the boat with the detector's electronics unit, put the coil with its 100 foot cable over the side, and you can search for anchors, cannons, outboard motors, etc. Attach the 16" coil with its short diver handle and you can cover an area quickly when searching for those larger targets.

One detector with a few different coils can do the work of two or three different detectors. The Pulse 6X and 8X can be used on land, dive to 200 foot depths, or deployed from a boat.