Dummy Door Spindles are for non-turning doorknobs. This is a useful option for doors where the knob is not connected to a latch or lock. Surface mount spindle to door then simply screw on knob with 3/8-16 thread. *
additional: Dummy Door Spindle 3/8-20 thread
Replaced an old door spindle with worn threads and 1in square base. While there was a 1 in square cutout in the door, I needed 2 forestner bits for the new spindle with a 1in circular base. The 2 forestner bit was a 3/8 in bit to accomodate the weld bump on the back of the circular base. The new spindle works fine after the 2 forestner bit drillings. I used new screws as the ones supplied probably would not hold.
Great service from Paxton.