This pneumatic 5-pc. Milton (S-213) A-Style coupler/plug air accessory kit includes a variety of couplers and plug air fittings with a 1/4" basic flow size (air handling capacity). Milton A-Style couplers are rust-resistant and made of steel, while A-Style plugs are made of case-hardened steel and are plated to resist rust. These couplers are for air shop use and are push-type. Simply push the plug into the coupler to engage, and pull back the sleeve to remove it.