The model No. 72 Auto-Vent is a fast venting valve of the expansion type, up to 75 lb. pressure. For vertical or horizontal mounting on convectors, baseboard, and freestanding radiators. 1/8" I.P. Male connection, 1-1/4" x 1/2". All expansion and contraction of the single nonporous, composition disk is confined to 4 vent ports. Manual venting and tight shutoff are controlled by a valve cap with screwdriver slot adjustment.