This was purchased to replace a 1.5mm top that did not have a zipper and was a pain to get on and off. That top was used both as a main layer in warmer water and an underlayer to a full wet suit in cold water. While the NRS jacket has yet to be used in the water, it feels great, appears to be high quality material and is much easier to get on and off. It also gets good reviews from other sites. This was for a male 5-7 and 145-150lb with an athletic build and a small was a good fit for them and it could have been a bit smaller as there was still a small amount of excess material the waist. The arms and shoulders were tight but without feeling any restriction of swimming or rowing movement.