the Th-40 came first then Hydro-force came out with the SX tools then Turbo-force coppied quickly the 15 " to keep up with the Jones's .
Hydramaster's RX15 is made by Hydro-force it's the same exact machine private labeled.
If you got the tool for free. sell it quickly unless you have a
Vortex or bestie TM. You need 3500 to 5 K water pressure to efficiently run it. As stated in another post it's too big to maneuver in most homes efficiently but more importantly the psi from most TM won't drive the spraybar fast enough to complete the spinn without the spiral affect. You end up having to travel half as fast to avoid the clean spirals on the surface you're cleaning.
Overall the dumbest idea they came up with. As the inventor of the original turbo and turbo-hybrid tools, the idea for me to make a larger tool died after the first prototype in 1999. It's too bad the two companies decided to go ahead with the (bigger is dumber) idea to make a 15" spinner.