Assos is kinda between Italian and American sizing. They make stuff really stretchy, so it fits a wide range of sizes. GBW is my favorite brand, because it is A-grade, and is more available on sale than Assos, but Assos makes A-grade stuff, no doubt about it. The Unos now have the S5 pad. Niice pad. I have it on the Winter tights and Mille FI bib shorts. But GBW and other mfrs buy Assos pads, under the Cytech Elastic Interface Techology brand. A great pad, and saddle matched to you, and some butt creme, is like, "I can ride all day until my legs give out." If you have to stand up because of burning, you need to do some changes. I mean a little standing up to restore circulation is fine, but if you are feeling abrasion burn, and are in serious pain, you need to re-figure things.