I purchased these shorts thinking that they were the polyester/spandex material and was a little bummed when they came and I saw they were nylon instead. However, when trying them on, I realized they are a more lightweight nylon material. They feel like the portland pants so they aren't as thick as a typical nylon/spandex. I would have preferred a polyester blend and will have to try the pinstripe version of these because they are but I do really like these shorts. They did slip a little in the waist for me when wearing them but not bad. I'm 5'4" with a 25" waist and 37" hips and purchased the Xs.