Loading... Please wait...The 2/1mm O'Neill Hammer Vest keeps the chill off with 2mm neoprene in the chest/back and 1mm underarms for extra flexibility. Made of 100% superstretch neoprene, this vest will really move with you in the water! Features durable flatlock seams, and a boardshort connector. Great for all water sports, especially if you need ultimate range of motion.