Optical sensor w/ magnetic mount

This sensor plugs into your FMM and, using
reflected infrared light, will signal your Apex when it changes state from
being wet to dry or dry to wet.

This sensor can be used for constructing your own
ATO (auto-top-off), as a high-level warning sensor in your sump, water storage
level sensor,

and much more. Included are a fastening nut and
silicone washer. These sensors are sold individually.