A must have for any Ductless Mini-Split System. FlareSeal® is a revolutionary product to address flare leaks in HVAC or Refrigeration flare connections. The FlareSeal® is a copper seal coated with Loctite. The Seal has multiple rings on the sealing surfacte to provide a crush connection and multiple points of sealing. The seal snaps securely onto the male fitting in any orientation. The Loctite® coating compensates for any imperfections in the surface. The kit for sale was specifically designed for Ductless Mini-Splits. In general, systems with typical ratings of 30,000 BTU, 36,000 BTU or 42,000 BTU will have a 3/8" discharge line and a 5/8" suction line. This kit contains (2) 3/8" seals and (2) 5/8" seals, all you need to complete a confident leak free ductless mini-split system install. PLEASE REFER TO OEM LINE SIZES BEFORE ORDERING. The outer diameter of the copper lines match the FlareSeal size needed. There are some systems in this range of BTU's that have different line set sizes. Installation is super easy.1. Make sure flare surface is clean of debris2. Clip the FlareSeal® squarely onto the male fitting3. Tighten with torque wrench to Mini-Split manufacturers recommendations FlareSeal® Recommended Torque Settings1/4" 13-17 ft-lbs3/8" 24-31 ft-lbs1/2" 36-45 ft-lbs5/8" 45-60 ft-lbs3/4" 66-88 ft-lbs Please check our other auctions for other sizes and kits specifically designed for Mini-Splits and VRV systems.