Add 2 sensors and you get the following levels, empty, 1/4, 1/2 and 3/4-full. Included: 2 sensors with 1 m cable length, 1 extra sensor tape, 1 3M wet wipe, and English instructions.
Upgrade Gobius 1 to Gobius 4 for waste tanks
For waste tanks
$117
Available on back-order