Screws on to most any folder Hardened 416 Stainless Hardened set screw .40" long .28" diameter .130" blade slot Includes 1/16" Hex Key Wrench We had these custom made for us. Use these thumb studs to add onto a folding knife blade (like a Buck 110) to make it a one handed opener. Compare these to other bolt on thumb studs for quality of materials and construction. NOTE: You are ordering 1 at a time. We are showing 2 studs here for clarity of illustration. Feel free to order several!