100% NylonThe product are single picatinny rails. Allow the attachment of various 1913 Picatinny rail-mounted accessoriesCan position just enough rail area exactly where you need it for each accessory, available in four lengthsRails come in L2 Size (5 Slots)L3 Size (7 Slots) L4 Size (9 Slots) L5 Size (11 Slots) 4pcs setUltralight rail with solid polymer construction and low profile design reduces bulk. 11-Slot 0.56Oz, 9-Slot 0.48Oz, 7-Slot 0.36Oz, 5-Slot 0.28Oz, much lighter than aluminum alloy, high strength and good safety, the material installed on the metal surface will not cause damage to the main structureInjection molded from a proprietary reinforced composite for enhanced strength and durability while remaining lightweight, Rail Sections also feature beveled ends to reduce snagging and eliminate sharp corners and edges.",