Many years ago I bought myself a long sleeve radiator rash shirt from my local surf shop to keep warm in the water. My daughter occasionally borrowed it as well. The ribbed stretchy material around the neck and sleeves eventually lost its shape and I just cut it off as it wasn't essential nor needed for structure. It continues to work very well for me. My niece recently has taken up triathlon so I’ve just purchased one for her for Christmas, and a spare one for me. It is stretchy, with a 0.5mm silver coloured neoprene lining. It keeps me warm so I can still swim laps at the ocean pool when it’s 18 degrees pool temperature. I love that it is of good quality, and does the job of keeping me warm. Also I had to change my size, I’m a women’s size 8, my old rash had size S but I thought seeing as I bought it so long ago, they’ve changed the women’s size from S/M/L to 8/10//12. I purchased a women’s 8 for me and it was too tight. Bob from Radiator sent me a mens S, as well as ladies size 10. The mens small fitted me better than ladies 10. He also sent returned parcel bag, too easy! 100% recommend the rashie top and the company.