When you are wearing a traditional rash guard, it is typically tight fitting and you have to stretch it onto your body. Then when you wear it into the water and get out, you are suddenly wearing some saggy waterlogged shirt that is not keeping you dry or protected from the sun. As you know, repeated use of that rash guard results in a floppy top that no longer has its UV protection and is falling apart. The Sharkskin Rapid Dry long sleeve is designed to have a loose-fitting stylish cut. Thanks to its cut, it can be worn on its own or over the top of another shirt or thermal gear. Its UV protection is SPF 50 in the water, out of the water, wet or dry. The high quality of material is much more durable and longer lasting than traditional spandex and will hold true after prolonged use in chlorine or salt water. Finally, there is the Rapid Dry factor. This top will not get water logged and sag, in fact it will be dry within minutes of leaving the water. It is perfect to wear in any outdoor activity, especially those involving water. Advanced water-repellent technology makes it dry in minutes Super durable even with prolonged use in chlorine and salt water SPF 50 sun protection in and out of the water Stylish cut with multiple color choices Sizing Guide GUIDE TO HELP YOU WITH THE BEST FIT FOR YOUR ACTIVITY The first thing to consider is what watersports activity you will use your Sharkskin garment for: Scuba Diving, Snorkelling and Swimming (where you are typically fully submerged in the water) - either by itself or underneath a wetsuit your Sharkskin garment should be a &';firm&'; fit.General Watersports Activities (where you are typically in and. out of the water or just splashed with water).You can opt for a slightly looser fit for the tops - particularly for very active watersports where you are rotating your torso and having a slightly looser fit will add to the comfort. Bottoms should be a &';firm&'; fit.To ensure a looser fit opt for the higher end of the sizing scale when comparing your measurements to the size chart. OTHER CONSIDERATIONS If you are &';average height&'; compared to your weight, in other words, you fall between the key parameters for weight and height, the guide should be straight forward, and detailed measurement is not required. If you fall outside of the &';average&'; please use below as a guide. You may need a different size top and bottom - so please measure both rather than choosing the same size automatically.When measuring for a top you should measure the widest part of your chest and the narrowest part of your waist. When measuring for a bottom you should measure the widest part of your hip and widest part of your thighs. When making your selection use previous experience along with these measurements to guide you. If you&';re tall and thin you are best to maintain a firmer fit even if it&';s a bit short in arms and legs. XXS XS S M L XL 2XL 3XL 4XL 5XL 6XL 7XL 8XL HEIGHT 65.4" - 68.1" 66.3" - 69.1" 67.1" - 70.1" 68.1" - 71.1" 69.1" - 72" 70.1" - 73" 71.1" - 74" 72" - 75" 73" - 76" 74" - 77" 74" - 77" 74" - 77" 74" - 77" WEIGHT 99.2lb - 121lb 121lb - 143lb 143lb - 165lb 165lb - 187lb 187lb - 220lb 220lb - 254lb 254lb - 276lb 276lb - 298lb 298lb - 320lb 320lb - 342lb 342lb - 364lb 364lb - 386lb 386lb - 408lb CHEST 30.3" - 32.7" 33.1" - 35.4" 35.8" - 38.2" 38.6" - 41.3" 41.7" - 44.5" 44.9" - 47.2" 47.6" - 50.4" 50.8" - 53.1" 53.5" - 56.3" 56.7" - 59.1" 59.4" - 61.4" 61.8" - 63.8" 64.2" - 66.1" WAIST 24" - 26.4" 26.8" - 29.1" 29.5" - 31.9" 32.3" - 35" 35.4" - 37.8" 38.2" - 40.6" 40.9" - 43.7" 44.1" - 46.5" 46.9" - 49.6" 50" - 52.4" 52.8" - 54.7" 55.1" - 57.1" 57.5" - 59.4"