I use one with an aquatica housing pretty regularly, and it works very well. There is a cup that sticks to the inside of the housing to hold the trigger cable from the camera, and a disc that sticks to the outside. The outside trigger mechanism (with the cable to the hand held trigger) pressure fits over the disc. The setup works well and everything seems very well made. They even made mine with a custom cord length. My only complaint is that the cup on the inside of my housing did not stick well (the aquatica housing is kind of textured inside), so I eventually glued it on. Also, occasionally if I am jostling the setup the trigger can come off of the outside disc. To remedy this I often cable tie (zip tie?) the cord on to the housing handle. This could be something to be careful of on a pole-cam where you are dunking it or swinging it in the water quickly. But, I do like that I can quickly switch from remote trigger to handheld by just popping the trigger off.
I should also note that the field generated by the trigger mist be quite strong because I had a hard time finding a convenient spot inside the housing to line up the cup with the outside disc. New housings don't have much flat surface on them. So they are offset a bit, but it still triggers every time.