Understand Metatarsal Foot Protection. The metatarsal protection standard is known as ASTM Mt75, MI75, C75. Met guards protect the metatarsal bones against impact on the top of the foot. There are several types of met guard protection Full Metatarsal Protection that covers not only to top of the foot, but the sides as well all the way down to the sole of boot. Flexible Metatarsal protection covers just the top of the foot, not the sides and general permits more flexibility to squat and otherwise flex the met guard. There are several materials used for metatarsal protection. Full metatarsal protection is accomplished with a full steel cap such as with the Ranger 2145 and Ranger 2155 boots. Viking Footwear has several Full Metatarsal boots, the VW49 and VW49T Miner49ER boots that use ballistic nylon, kevlar and other fibers to created a solid full met guard cap. Flexible, waterproof rubber metatarsal boots are available in Ranger, Viking and Servus brands. Some internal met guard leather boots use Poron for the metatarsal protection. Poron is a flexible material that instantly firms up upon impact. These ASTM I75 boots are available from Thorogood and Timberland Pro.