Mustang Survival Sentinel Replacement Outer Layer for MSD644FEATURES This replacement outer shell is the second layer in the Sentinel Series 2 layer drysuit, and features a heavy duty CORDURA protective outer layer that is reinforced in key areas with 1050 Denier Ballistic Nylon to guard the entire inner layer from grease, oil, rips and tears. Our Sentinel dry suits are in use by US Coast Guard and validated by NAVAIR, SAR Model Manager Office, Naval Special Warfare and water rescue professionals. Multi