I'm using this suit under Alpinestars Atem V3 leathers. The leathers came with a zip-in liner that didn't work very well (Velcro always hangs up in weird places), so I bought this under suit. I went larger than I need according to the waist measurement, which is 36" in the LG suit. I'm an older guy, 6'-2", weigh about 175 lbs., 34" waist, long torso. The LG suit is a bit short in the legs and arms for me, so if this description fits you physically, you might want to opt for XL. (I'm sticking with the LG because I'm afraid the waist, thighs and arms will be a sloppier fit if I go with the XL.) The suit appears to be the same as the Cortech suit, but costs a fair amount less, so that's a real plus. My rating is based more on the sizing than on the quality of the suit itself -- the fit seems biased toward folks who are shorter and chunkier than me. Still, I can get in and out of my leathers much easier using this suit than I could with the liner provided by Alpinestars.