A double check valve (10) with two separate elements (20, 25) individually movable to close the valve and collectively movable to open the valve. The separate elements are independently closing the valve, and collectively controllable to open the valve, to allow pressure release or to allow injection of fluid (e.g. lubricant). In an example, the double check valve includes two separate check valves with a stinger element (30) between them which is operable to internally sting the one check valve when (e.g. by action of) the other check valve is stung by a user (e.g. using a stinger means) thereby to open both check valves individually and the double check valve as a whole.