A rotationally adjustable valve is disclosed whereby the user is able to control the flow of fluids from complete shutoff to maximum flow by rotating the body of the valve, said rotation being axial to the flow of the fluid. Additionally, the user is able to attach high and low pressure test probes directly to the valve, as it is rotatably adjusted, so that additional equipment is not required next to the valve. An embodiment of this invention includes the use of an adjustable Cv disk to set the maximum flow of the valve, rather than just create a simple 180° on/off, very similar to a current 90° ball valve that this device will replace. All of the problems associated with the ball valve have been minimized including creating a linear relationship between the percentage open of the valve and the percentage of maximum flow of the valve.