Flexfab silicone rubber high temperature duct. 500 F. 2 ply. 16 psi max pressure or 13 in Hg max vacuum. 141 inches length and 4 inch ID. Hose is flexible and pliable, but a bronze coated spring-steel wire support helix prevents it from collapsing.
Military p/n 7986300. New/unused. This is an uncut factory produced length.