Ball Valves.

A ball valve (like the and are one of the family of valves called quarter turn valves) is a that opens by turning a handle attached to a inside the valve. The ball has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed, the hole is perpendicular to the ends of the valve, and flow is blocked. The handle or lever will be inline with the port position letting you "see" the valve's position.

Used to control the pressure, air or liquid flowing through pipes.