Staples are a type of metal fastener used to secure or bind materials together. Product details about the GARDNER BENDER - MMS-3102 Staples. Staples, 1/4 in Leg L, Metal The robust material is built to withstand pressure and resist wear over time, making it suitable for tasks that require a sturdy fastening solution. Staples are typically made of steel wire and are formed into a rectangular or U shape.