Permatex Surface Insensitive Threadlocker Blue is a medium/high strength threadlocker for general-purpose applications. Especially well-suited for 6mm to 20mm fasteners that have a slight oil film, this threadlocker prevents loosening due to vibration. Oil resistant and removable with hand tools for easy disassembly. Applied as a liquid or gel, threadlockers are superior to conventional lock washers, nylon inserts, and other mechanical devices because they secure the entire fastener assembly against loosening from shock and vibration by filling the space between threaded metal parts, curing to form a tough, adhesive bond and seal. They also seal the threads against leakage, preventing rust and corrosion.