S.R.Smith TURBOTWISTER Assembly And Installation Instructions Manual page 15

13. Drill a 1/4"Ø pilot hole through the center of the 6 circular indentations around the perimeter of the
Pedestal / Runway connection. Then install a 3/8" x 3-1/2" Lag Screw (9) and 3/8" Flat Washer (4)
as shown in Figure N.
Figure N
15