Since the cutting blades are attached on both sides, it can cut both clockwise and counterclockwise.
Chamfering work is performed by pinching the tool with your fingers and rotating it left and right while pulling (pressing) it into the drill hole.
To insert the blade into the drill hole, insert the blade vertically while pressing the knob with your fingertip, then remove your finger from the knob and the blade will return laterally. Do the same when pulling out.