Air universal coupling (US type) Material: Carbon Steel Zinc plated Size:1/4",3/8",1/2",3/4",1" Air universal coupling (US type)Material: Carbon Steel Zinc platedSize:1/4",3/8",1/2",3/4",1"These fittings are most commonly used on hose lines connecting pneumatic tools to a compressed air source and are sometimes referred to as 'Crows foot' or 'Chicago' couplings. Chicagao coupling (all type)