Item Type: Expansion Bolts Material: 304 Stainless Steel Screw Rod Diameter: Approx. 6mm / 0.2in Expansion Bolts Length: Approx. 90mm / 3.5in Application: Widely used in protective fences, anti-theft doors and window, canopies, air-conditioning outer frame fixing, home improvement, engineering, etc. How to Use: 1. Choose an impact drill bit with the same diameter as the expansion screw casing and install it on the electric drill to drill the hole. The depth of the hole is the same as the length of the expansion bolts, and then knock the expansion bolts kit into the hole together. Note: do not put the nut unscrew it to prevent the bolts from falling into the hole when the drill is deep. 2. After tightening the nut 2-3 buckle, it feels that the expansion bolts is relatively tight and not loose, then unscrew the nut, and align the fixing piece with holes on the fixed item to the bolts and install the gasket or spring installed on the outside Tighten the nut with the washer.