General Specialties Universal Top of Pole Mounts 

Made by General Specialties, the Universal Post Mount is the strongest you can buy. Adjusts easily to seasonal sun angle.  These Universal Post Mounts have a welded steel frame with 6061 aluminum rails for mounting PV panels. Designed for 35 lb./sq. ft. wind loading.  Stainless nuts & bolts are supplied to attach modules. Grade 5 and 8 assembly hardware is included. Vertical base pipe is not supplied, you obtain it locally.  Pipe size for this mount is 4"/Sched 40 or 80. Very easy to assemble, great instructions with pictures included, holds panels securely for decades.