Precision Lock FB24 24 mm Forstner Drill Bit for PLS24PRO and PLS24PROXHD

The FB24 is a 24 mm Forstner bit, so it bores a 24 mm diameter flat-bottomed hole. That is the hole size the PLS24PRO and PLS24PROXHD installations call for, which is why the bit is sold to go with them.

It is matched to two: the PLS24PRO and the PLS24PROXHD. Precision Lock sells the FB24 as the 24 mm bit for those, so if you are installing either one, this is the bit that bores the prep. For any other unit, check the hole size that unit requires before assuming a 24 mm bore is right.

The FB24 is ordered on its own. It is a separate model in the Precision Lock line, sold as the 24 mm Forstner bit for the PLS24PRO and PLS24PROXHD, so if you need the bit to cut the prep, add it to the order rather than assuming it ships in the box with the unit.

A Forstner bit cuts a clean, flat-bottomed hole and stays on center, which is what a hardware prep needs when the part seats into the bore rather than passing through it. Precision Lock specifies the FB24 Forstner for the PLS24PRO and PLS24PROXHD for that reason. A spade bit blows out the exit face and a hole saw leaves a plug and a rounded, ragged bottom.

Precision Lock lists the FB24 as a commercial door hardware item. It is an installation accessory, a bit a contractor or locksmith buys to do the door prep, not a finished piece of hardware that stays in the opening.