The Kent/Elster V100 water meter contains a magnet mounted on the last counter digit as well. A black plastic cap can be found on the side of the meter.
Remove the cap. Two cavities will become visible. Insert the FLS02-T1 water probe all the way into the biggest cavity.
Secure the probe with a plastic cable tie.
Configure the FLM pulse port's meter constant to 0.5L per pulse for this specific type of water meter.
