Nylon washers are used to create a seal between metal-to-metal 1/4" flare fitting connections. Most often used with stainless steel ball lock quick disconnects to prevent leaks. These washers are not necessary when connecting female flare fittings to plastic male flare QDs that have a plastic washer built-in.
Flare washers are easy to misplace so we always recommend keeping spares on hand.
Comes in a convenient zip lock bag.