We find the clearest way to express the length / depth of liquid level alarm products is with what we call “working depth”. That is what matters most, and eliminates the confusion over the overall length and the mounting apparatus.
The mounting apparatus may differ from the picture for different models but the “working depth” will always be the distance that the float extends into your tank.
We have shown a model IS-T so the float can be clearly seen but the same measurements apply to all the level alarm products.