A flow stopper has an elongated shape for positioning in a tubular cavity of a check valve. The elongated shape has a concave section such that the flow stopper can impact a line running along an inner surface of a housing forming the tubular cavity in a lengthwise direction of the tubular cavity. The concave section allows the flow stopper to impact the housing with a first point of contact and a second point of contact on the line, and the two points of contact are separated by a gap where the flow stopper does not contact the housing. The flow stopper may include a first and a second ball where the balls are connected by a stem. The flow stopper may also include a plurality of balls that are not connected to each other. The flow stopper may include a ball connected to a stem.