DeltaFAUCET DF5718SS 18" x 1 1/4" Concealed Screw Bathroom Safety Grab Bar, Stainless Steel

The #10 x 2.5" screws supplied with this are for the most typical application, through drywall and into a stud. The Phillips heads strip out before they go all the way into the stud. I used the correct drill size (7/64") for the pilot holes, but most 7/64" bits are not long enough to go the full 2.5". When I used an impact driver, the heads stripped while there was still more than 1/2" to go. When I tried to drive them in by hand, I could not get them in as far as the impact driver did. I ended up using other screws that went flush with the impact driver and did not strip out.