Permatex’s Medium-Strength Threadlocker Blue is ideal for all nut and bolt applications 1/4? to 3/4? (6mm to 20mm). Threadlocker Blue eliminates need for stocking expensive lock nuts and lock washers and locks and seals while preventing parts loosening due to vibration. Protects threads from corrosion. Threadlocker BLUE is easily removable with hand tools for easy disassembly