RIVERINE Men's Shapewear Neoprene Vest Hot Sweat Gym Shirt Side zipper Tank Top 80% Neoprene + 20% Nylon. Neoprene material keeps your body warm and heat up your core abdominal area making you sweat more while performing your daily activities. Comfortable, lightweight, stretchy fabric molds and moves with your body while performing any activity. Provides instant abdominal compression and lumbar support. Size tip: Use the Size Chart provided in photo on the left to choose the one fits you.