The original thought was: effective, "self contained", light weight, no straps, affordable to everyone.
The original CAT (Constant Applied Tension) was constructed of plumbing supplies. These were cemented together and turned on the lathe as required. The CAT was a taped on, pee-thru, device containing a spring to maintain tension. The initial tension was established through the threaded tensioner rod/pee tube.
The CAT II was much like the CAT, except I had gone to tapeless and had gotten rid of the spring, as it was easy enough to increase the tension manually. Also, "auto tension", through the use of the spring, turned out to be a negative experience. Holes in the outer cone were added for more grip. A rubber washer was added to help keep the outer cone snug against the skin.
The CAT II RO got rid of the copper tube and added an O-ring. Also, a ridge was added to the puller to enhance the grip. The holes in the outer cone were gotten rid of, due to the fact, that they were a source for irritation. Pee-thru was optional.
The next generation of the CAT II RO incorporated molded HDPE plastics for the puller and pusher. Pee-thru was phased out, as it was fairly quick to remove and re-install.
To this point, all CATs had used the threaded rod tensioning mechanism. This method could produce terrific tensions without the user even knowing it, until they were experiencing pain, some two hours later.
(2005) Now along comes the CAT II Q with molded components, tapeless, silicone outer cone (shaped to the puller, to prevent increased compression of skin, during increased tension), multiple length tensioning rods and a QUICK-GRAB/RELEASE tensioning system!
As of April 2011, the ties to hold the rod to the pusher have been exchanged for a "greener", easier method, consisting of an aluminum rivet and a piece of vinyl tape to hold the rivet in place.
Many of the improvements to the CAT series have been user generated. It's for this reason, the CAT II Q is the most advanced restoration device currently available!
I believe, I've maintained my original goals and made it a bit easier for the user to obtain their goals.