Maid O Mist Hot Water Disc Vent for vertical or horizontal mounting on convectors, baseboard, and freestanding radiators. This fast-venting valve of the expansion type features a 1/8" I.P. Male connection and can withstand up to 75 pounds of pressure. The compact size of 1-1/4"x1/2" ensures easy installation. The single nonporous composition disk allows for precise expansion and contraction, controlled by a valve cap with a screwdriver slot adjustment for manual venting and tight shutoff.