Z-Flex Z-Vent 4" Wall Thimble WIDE Stainless Steel Vent (2SVSWTEF04) 4" Wall WIDE Thimble Stainless Steel Venting Wall thimble is used for horizontal exhaust venting through the outside wall Wall Thimble is 10" x 10" and has an adjustable width from 5" to 10" Rated AL29-4C and is approved for Category I (vertical only), II, III & IV applications Contains a built-in, fail-safe gasket and locking band connection