These were early Middle Ages knee protection. Developed during the transition from Chain Mail and Plate armor, this was a first attempt to protect these body parts. Poleyn can trace it's development back to the Greaves of Ancient Greece and Rome. They could be constructed from thick leather or curved metal (fitted for the knee caps). Often lined with cloth (which lessened friction and injury), they were strapped on the body via support straps (leather). Many Archers and Spearmen (when they could get them), liked them for their mobility in combat.