Despite the negative opinions of the Ventz system I decided to give it a try because I ride year round and wear various armored jackets. I'm in Florida and the summers are +90 with the on road temps probably bumping 100.
I've used it for two weeks now and will not leave home without them. If I start out in the morning with 70 temps, I will carry them in my pockets and when the temps rise into the mid 80s, I insert them. There is no doubt that I am cooler with them then without.
My related observations is that the looser the jacket sleeve is, the more air flows to your back. Most of my jackets are Dainese with the slimmer sleeves, and even at that, I can feel air cooling my arms and getting under the back protector. Physics comes into play as you ride with them because the increased air flow will initially evaporate any perspiration and initiate a heat transfer process. As you continue to ride it will seem that there is less cooling, and that is a correct perception because the perspiration has evaporated and you are dry. However, If you stop at a light for more than a minute or so, as you pull away you will feel increased cooling once again from the evaporation process.
Second observation is that there is no discomfort from them. I suspect that any discomfort is an indication that the brake and clutch levers are not adjusted so that the top of the hand and forearm are in the same plane.
Third observation is that the back of the hand area will perspire under the Ventz. To me, that is not a show stopper and hardly notice it anymore.
My 2 cents is that they work for me......and that is all that matters to me.
