40570 Robinair Premium 1/4 Brass Cap With 3" capture chain features a split ring that fits neatly over a 1/4" flare fitting to capture flare cap when removed to prevent loss or damage. Never Lose that fitting cap on your recovery unit or tank again. Extra long skirting allow for a deep gasket, shallow "o-ring" type caps can actually depress cores causing leaks when over tightened. The gaskets in these are also replaceable, See 40083 for replacements.