For fine threaded fittings, choose LOCTITE^® 545. This thread sealant is perfect for small fittings in general, especially as used in hydraulic and pneumatic installations. The medium-viscosity product cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage from shock and vibration when cured. It's specially formulated to offer lubricity for the easy assembly of hydraulic and pneumatic fittings, and contains no fillers or particles that could contaminate system fluids, foul valves, or clog fine filters and screens.