I am a tennis player and I sweat a lot.  The lenses on these glasses are fantastic.  There is no frame, so your vision is not blocked in your peripheral vision.  this is very important when playing tennis since on service tosses and on many shots you are looking out of the corner of your eye to see the ball.  These glasses function great at this because they are frameless.  The nose bridge is very comfortable and tends to stay in place.  I have two complaints about the glasses which could have been improved, but weren't.  The previous version of these glasses (which have been discontinued) had two very nice features which THESE glasses do NOT have.  1) There is no adjustment as to angle of temple pieces where the temple piece meets the lenses.  Therefore if one ear is slightly higher than the other, these glasses will not be able to fully adjust to this (other frames have this adjusting feature, but I have found no currently available frameless sunglasses with this feature. 2) The temple pieces are made of very slippery (non-grip) material.  This is ALSO a regression from the excellent previous model where the temple pieces were made with slip resistant materials.  Therefore, the glasses sometimes ride down on my nose.  Too bad that they just couldn't continue to manufacture the old versions of these frames.  They sacrificed functionality for style and a cheaper manufacturing process, in my opinion.  Buyers should also note that there are two sizes to these lenses so that they can order the correct size for their face.