The SHARKSKIN High Performance Long Sleeve Top helps you achieve more in your training, competition and recreation sessions. A combination of the world&&';;s most advanced fabric technologies provides warmth on your core and flexible compression on your shoulders, arms and upper back for active watersports. The entire front and lower back uses Chillproof 3-layer windchill proof fabric to keep your core and kidney area warm. The front also has a half zip for 100% warmth when you zip up or vent when needed. The shoulders and arms are covered with a new Hydrophobic Nanotech Compression fabric that is infused with titanium to provide additional warmth. High compression helps speed recovery. Hydro-Lock technology repels water to minimize water absorption even when submerged for a truly hydrophobic finish. The shoulder area uses "posture right" kinesthetic panels that help with musculoskeletal form for all active watersports where you are using shoulder and arm rotation. The wrist has a welded-band cuff to keep it super secure and to stop it riding up when paddling or swimming. SHARKSKIN High Performance is specifically designed to help you excel in active watersports like paddling, ocean swimming, sailing, windsurf, kitesurf and all foiling watersports. Its long sleeve design provides 100% UPF50+ sun protection. Warmth on your core and flexible compression on your shoulders, arms and upper back for active watersports. Shoulder area uses "posture right" kinesthetic panels Excel in active watersports like paddling, ocean swimming, sailing, windsurf, kitesurf and all foiling watersports. UPF50+ sun protection Sizing Guide MENS XXS XS S M L XL 2XL 3XL 4XL 5XL 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" WEIGHT 99.2lb - 121lb 121lb - 143lb 143lb - 165lb 165lb - 187lb 187lb - 220lb 220lb - 254lb 254lb - 276lb 276lb - 298lb 298lb - 320lb 320lb - 342lb 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" 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" The Sharkskin size charts are made to be accurate for the type of fit you need for each garment. Provided that you measure your body accurately then you will get the very best estimate for size.VIDEO GUIDE TO HELP YOU WITH THE BEST FIT Under a wetsuit - if you are wearing Sharkskin(TM) underneath a wetsuit then you will need to make sure your Sharkskin(TM) garment is 'fitted&&';; so that it is firm on your body and does not bunch underneath your wetsuit.In and out of the water - if you are wearing Sharkskin(TM) by itself (not under a wetsuit) and are fully submerged or 'in and out&&';; of the water (EG - 'in and underwater&&';; watersports like SCUBA diving and snorkelling, and also general watersports where you are 'in and out&&';; of the water like surfing, foiling, wake boarding, kiteboarding, windsurfing, performance sailing, etc) then it is also best to make sure your Sharkskin(TM) garment is more 'fitted&&';; than loose. Out of the water - if you are wearing Sharkskin(TM) as a standalone garment out of the water 100% of the time (EG - SUP boarding, surfski paddling, recreational kayaking, snow skiing, sailing, as thermal wear for mountain biking and other outdoor activities, etc) then you may be more comfortable with a slightly looser fit to allow for better torso rotation and flexibility.Sharkskin Rapid Dry rash shirts - the exception to wearing Sharkskin(TM) 'fitted&&';; is the Rapid Dry range. Rapid Dry is designed to be worn slightly loose like your favorite T shirt. FIT TIPS - To ensure a looser fit then size up or choose the higher end of the sizing scale when comparing your body measurements to the size chart. To ensure a tighter / firmer fit then do the opposite. When putting Chillproof or T2 Chillproof garments on do the zipper up at the narrowest part of your waist and then pull the top down towards your hips. Once pulled down then continue to pull the zipper up, (per the video demonstration). You may need a different size top and bottom - so please measure both top and bottom measurements rather than choosing the same size automatically. 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.