Abstract: A marker for locating an underground object such as a utility line features an elongate, flexible body, with an aperture near one end. The aperture has a “keyhole” shape which imparts sufficient stiffness in the marker so that it does not readily bend or flex at the aperture when handling the marker, while also allowing the marker to break near the aperture when a firm force is applied to the marker.

Abstract: A valve for controlling flow of fluid through an aperture in a barrier comprises a valve body including a pin and having a continuous sealing surface surrounding at least one opening through the valve body, and a diaphragm of resilient material. The diaphragm has an opening surrounded by an inner margin and is disposed with the pin extending through the opening and with a main surface presented towards the continuous sealing surface of the valve body. The inner margin of the diaphragm is in a state of tension around the pin of the valve body, whereby the diaphragm is prestressed to a condition in which the main surface of the diaphragm engages the sealing surface of the valve body.