IST signature jumpsuits, constructed of high-grade neoprene in 5 mm thickness. 5 mm suits : Double Blind Stitching. Special printing technique on shoulders and chest areas offers extra durability in areas prone to high wear when diving with BCD. YKK #5 zipper at wrists and ankles. 5 mm suits : Super-stretch material at armpits and lower back area to maximize range of motion. Puriguard Fabric.