Mil-Spec Flex Hose. 1-3/4 ID x 16″ Long. HBD Industries p/n AD1712-24. NSN 4720-01-114-9254. Quality mil-spec surplus. Original application is on submarines. Would be great for cooling ducts on race cars, bikes, street rods. Original price on this hose was $764.37 EACH Every corrugation has its own butt-welded Stainless Steel Wire to prevent collapse, on the inside and outside Excellent bend radius. 14578 L2C9