LOCTITE 243 is a medium strength blue threadlocking adhesive that seals and secures metal nuts and bolts to prevent loosening due to shock and vibration.LOCTITE 243 is a general purpose threadlocker that provides a medium strength bond. LOCTITE 243 works on all metals, including passive substrates such as stainless steel, aluminum and plated surfaces. It is proven to be tolerant of minor contamination due to industrial oils, e.g., motor oils, corrosion prevention oils and cutting fluid.