These are the BEST js I have come across since another cotton mesh js went off the market.  This is really carefully stitched to avoid binding, cutting or twisting problems with the strap.  It dries fast after a hand wash.  It is soft to the skin.  Truly a great quality product.  No one comes close.  I'm sorry I loaded up on another brand before discovering these.  But two caveats.  A.  This js was part of the PRIME and now not.  B.  Reviewers were right about moving up a size to get a firm, but soft fit.  I can't imagine if I had got the L instead of the XL how it would have fit.  I'm a 36-38 waist.  The XL is for the 40's.  Even so, it fits like a glove.  No slipping.  No lack of elastic grip.  So thank you reviewers for helping me make the right size choice.  I think that those saying it was not necessary are those in the S and M sizes for which the situation may be different.  I suspect the difference is between small individuals and their relative small overall frames vs. large men and their heftier builds.