The roller is positioned proximate to a stack of flat mops in the pan and the roller rotates to engage a flat mop and dispense the flat mop out of the dispenser.

My calendar rolls over every time the ball drops in New York, and I've yet to see this cause any planetary cataclysm, except for theguy who has to mop out the drunk tank at the NYPD.

Just a twist of the handle is all it takes to wring out the mop.