This device is gravity fed in to the water stream at more or less soap from several seperate bins depending on which bin or how much you open the bin to add to the water.
You should also add a water shut off to this for lathering so that you are not just saturated with soap then immediately rinsed since the soap should be on you for a period of time.
It is similar to pressure washers that dispence soap but those require pressure to expel the soap and my product is a very inexpensive version of this being that it is made entirely of low grade plastic and is easily replace should it wear out.
The screw on design works exactly like a shower head and both the shower head and the soap dispenser have the same universal size screw on design which allows you to attach the dispenser between the shower head and the water inlet in less than a minute.
Thanks for your interest and if you can think of a better idea to add to this we just might make some plastics company rich while all of us do the thinking! Ha!