This frame design is truly a mainstay for general aviation. The strong, sturdy, double ball-bearing and ¼” cold rolled steel design will offer you many years of exceptional service. Having a ¾” collar or female thread looking up allows you to simply screw the extension rod into the awaiting threads for easy installation. We offer this frame in 18”, 24”, and 36” diameters. Our BB Series frames have just gone through a re-design! We recently made the ring attachment arms one piece, both top and bottom. This allows us to make a very strong weld on top and overall creating the strongest frame on the market. We then put a state of the art black powder coat finish on the frame for added durability. (Click the image on the left for a larger view.)