Poron XRD 155 is by far the best material I've found yet for the Freeform panels. This poron is very different from the Toklat and Jenx poron. It gives the best weight distribution, and helps the horse move freely. I have been using it and my horses backs have been vetting through the endurance rides with all A's. Keeps my guys happy when they can move nicely and with ease.
The Poron XRD also helps with heavier riders get the right fit and weight distribution. You can hold a heavy ball baring chest high and drop it to the floor on the Poron XRD. The ball baring never even bounces. Amazing .... I'm not on board with using this in the pads, I don't feel it breathes.
Also available in an English Style Panel size.
