Flare tube fittings have a tapered end that fits into tubing with a flared end. These reusable connections are secured with a sleeve and threaded nut and tightened to create a pressure-resistant seal. These fittings resist mechanical pull-out, are suitable for use with thin wall tubing, and require no flame or propane. 45° flare fittings are used with refrigeration and vacuum lines, fuel and gas equipment, and plumbing. Inverted flare fittings resist vibrations when used with refrigerant lines, hydraulic brake lines, and fuel lines. Bubble flare fittings are primarily used with automotive brake lines.