LOCTITE 243 Primerless, Oil Tolerant, Medium Strength, Removable Blue Threadlocker is an oil tolerant, removable, medium strength, blue threadlocker designed for the locking and sealing of threaded fasteners between 1/4" and 3/4" (6 to 20 mm). It not only works on active metals (e.g. brass, copper) but also on passive substrates such as stainless steel and plated surfaces. It tolerates minor surface contaminations from various oils, such as cutting, lubrication, anti-corrosion and protection fluids. LOCTITE 243 is the recommendedreplacement for LOCTITE 2440.