The Martin Yale Master® EP323 Duo™ is an innovate electric hole puncher that allows for both 2-hole and 3-hole punching for any standard US ring binder. There is no complicated change over or adjustments needed to switch from three and two hole punching, because each side of the puncher is dedicated to one action; so one side is for 2-hole and the other is for 3-hole. All you have to do is insert you paper into the proper feed opening and then press the corresponding button on the top of the machine. Both sides will punch through as many as 12 sheets of paper* at a time and cleanly dispose of paper waste into a small waste tray at the bottom. The option to use either a detachable power cord (included), or six AA batteries (not included), as well as the small footprint make this paper puncher portable and convenient. When you buy the Martin Yale Master® EP323 Duo™ 2-hole and 3-hole electric punch online, you are investing in a small, but powerful little binder punching machine.