3Starinc’s 3MC100 Mast Pipe Mount Bracket for Outdoor Low Intensity Obstruction Light Controller provides a means to Mount the CB04O LIOL Low and Medium Intensity Obstruction Light Controller anywhere along a Vertical Mast, Pipe or Round Structural Member from 2-1/4 to 5 inches in Outside Diameter. Kit Comprised of Stainless Steel Mounting Plate and Hardware.
This taken from the FCC:
Antenna Tower Lighting and Marking Requirements
Antenna Tower Lighting and Marking Links