and is positioned on the surface of the pipe 10 between the top end 11 and bottom end 12 the vent 13 is a hole that allows air in the drain line between the sink drain and the drainline trap to be released from the drain line as it is displaced by liquid draining from the sink the vent 13 may be any shape but is preferably substantially circular the vent 13 has a diameter that is sufficient to allow air to escape and may be as small as a pinhole the preferred vent 13 diameter is about 0 375 inches a vent 13 of about 0 75 inches to 1 inch in diameter is shown in the figures for the purpose of clarity using the top end 11 as a reference the vent 13 may be placed any distance from the top end 11 that allows proper air release this distance may be chosen depending on the existing sink installation in which the vented tailpiece will be used specifically the pipe 10 may need to be longer or shorter to accommodate the existing sink installation for standard sink installations the pipe 10 is typically 6 8 inches long the preferred pipe 10 is about 8 inches long with the vent 13 placed at the midway point of the pipe 10 further the preferred pipe 10 may be modified to fit the sink installation by cutting off part of the pipe 10 from the bottom end 12 and if the pipe 10 is not long enough for an existing installation it may be fitted with an appropriately sized standard plumbing pipe extension.