Includes: 3 pole, 3 position rotary switch, ¼" output jack and black chicken head knob. Hammond 1600A series transformers provide 'easy wire secondary' impedances of 4, 8, or 16 ohms. We now offer a selector switch, pre-wired and complete with ¼" output jack. Follow simple instructions provided to wire transformer secondary to switch, mount switch and ¼" jack in separate 3/8" diameter holes in chassis and you'll easily be able to select output impedance as necessary. (Not recommended for 1645A or 1650G) (See P-H1600 for a selector switch to work with Hammond 1600 series transformers.)