Perko Delta Universal Replacement Boat Stern Light This Perko Delta Universal Replacement Boat Stern Light features a universal type, fit and angle. It includes a reduced glare globe that preserves night vision while under way and a fully clear globe that offers cockpit illumination. With two collars, it provides two key slot screw positions so that it fits more popular bases than any other light on the market. The tilt range can be easily and widely adjusted further to match most custom bent po