Abstract: A check valve suitable for use with a sealing sleeve, the check valve comprising: a body defining a bore having a first open end adapted for connection with a dispensing apparatus and a second open end adapted for connection with a delivery apparatus; a core slidable in the bore between a closed position and an open position; sealing means for sealing between the body and the core when the core is in the closed position, so as to prevent flow of fluid between the first and second open ends; biasing means for biasing the core into the closed position; the distal end of the second open end being provided with a first flange which extends radially beyond the outer edge of the body. Wherein the first flange is provided with one or more surfaces which are substantially non-perpendicular to each other.