Roto-Moulded Impact Armor Built for Extreme Missions. The rSeries Mil-Standard cases have been designed to meet the most exacting military specifications. They are roto-moulded of impact-resistant/UV stabilized LLDPE for strength and durability, featuring airtight and waterproof construction with solid stainless steel latches and hinges that will withstand the most demanding shipping conditions. SKB's rSeries cases come standard with an empty interior, and some models are available with: cubed foam, layered foam, padded dividers, and a pull handle with wheels.