Ostomy pouches

An apparatus comprising a controllable flow rate, filtered, vent for an ostomy pouch, the vent having a plurality of outlets and a device for controlling the rate of flow of gas through the vent, the device comprising adhesive sticker means which can be positioned and re-positioned to selectively expose or cover one or more of the plurality of outlets, and thereby regulate variably the rate of flow of gas according to the outlets exposed, and a body-side device for attachment to an ostomy pouch, the body-side device comprising an adhesive wafer for directly or indirectly securing the ostomy pouch to a person's skin, and a coupling portion for releasable fastening to the pouch, wherein the wafer, or a cover layer provided on the wafer, is provided with guidelines for enabling a person to cut the wafer to a desired aperture size, the guidelines including at least one generally circular guideline, and at least one generally non-circular guideline, and wherein the wafer is secured to the coupling portion around a closed loop line of attachment, the line of attachment is defined by a combination of a circular shape and a race-track shape, the combined shape corresponding to a silhouette of one superimposed on the other.