Another problem with some weighted vests is the constriction of breathing and overheating due to the use of heavy, non-breathing materials such as nylon and neoprene. The latest developments in weighted vest products offer comfortable weight vests with cool wicking fabric that allow full range and direction of movement, chest expansion for breathing, open sides connected with lacing, and low profile design allowing a vest to be worn under clothing or football pads, unlike traditional vests made of nylon or neoprene.