As some have mentioned they run a little bit small, but it depends on how you like to wear thongs. I prefer a snug fit so the large fit me great, but more snug than most large sizes. If you have a large package it probably won't work for you, growers are ok. Material is fantastic, and construction seems solid. I have no real complaints! Also when on sale the price makes it a no brainer. A size guide would obviously help people, but might scare some away.****Update - I have ordered another pack in my normal size which is medium and yes they are a little tight but I think this is the intended design. I actually like my normal size better since it really keeps everything in place, no matter what kind of exercise you do. Almost like a thong jockstrap, but the material is so soft I love it! Again if you have a large package area or are actually bigger than you think this probably won't work for you. Average overall size guys and your golden.