The Nu-Calgon 4289-04 NuLock Flange Sealant is an anaerobic-based formulation is for metal fastener thread locking and sealing; including sealing of metal flange connections. NuLock Flange Sealant is especially useful for flare fittings used in the HVAC/R market to improve their seal ability and thread locking of these mechanical fasteners that are susceptible to leakage due to vibration. An anaerobic-based sealant remains liquid until isolated from oxygen with metal contact in fitting threads. To cure, the product requires lack of oxygen in close contact in fitting threads. Product cures due to lack of oxygen in close contact of metal surfaces. The process results in a chemical resistive cross-link polymer with great adhesion to metals that provides both a thread sealant and locking - depending on the application. NuLock Flange Sealant is highly resistant to heat and vibrations, with excellent chemical resistance and temperature range. Simple hand tools are required when fasteners need to be dissembled. THE NU-CALGON 4289-04 NULOCK FLANGE SEALANT IS FOR PROFESSIONAL USE AND SHOULD ONLY BE USED IN ACCORDANCE WITH ALL REGULATIONS AND PROPER SERVICE PRACTICES. PLEASE SEE PRODUCT LABEL OR CONTACT NU-CALGON DIRECTLY FOR USE INSTRUCTION. IT IS RECOMMENDED TO UTILIZE THE APPROPRIETE PPE (PERSONAL PROTECTIVE EQUIPMENT) DURING APPLICATION.