Cotton fabric mil spec mil-f-4143,type i,sea blue,17.00 in. W,18.000 in. H,three layers of insulation 0.500 in. Thk fiber glass fastened to inside wall,cover to be marked w/sperry trade mark,mk 23 gyro compass,w/white characters,all parts including thread and slide fastener flaps to be fungus resistant and mildew proofed