This lot includes 2 pins (one small and one large tip).
Make sure batteries are removed before installing or changing bits.
To install a bit:
Select a bit based on the thickness of line you want to make, then insert the flat end into the opening of the chuck (about 1/4").
Insert the allen key (included with the engraver mentioned above) into the screw on the side of the chuck and tighten the screw until it holds the bit firmly in place.