Things can get chilly even when the water's warm and the sun's out, so Patagonia designed the R1 1. 5mm Women's Long Sleeve Top to cut the chill when you're waiting for the perfect set to roll in. The stretchy 1. 5mm neoprene is laminated to a recycled polyester face that keeps the wind from sucking away all your core heat, while flatlock seams prevent chafing and are glued, bartacked, and Melco reinforced in key areas to lengthen the life of your suit. There's a hem drawcord as well, to ensure a snug fit, and the cuffs are heat pressed to form a snug seal against cold water and chilly air.