After reading an ad on E-bay, I won't buy or recommend anything from FBO. Read for yourself. I have no affiliation with either party.
http://www.ebay.com/itm/221434174684?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT
WOW!!! Selling yourself and product by calling the other guys thieves is bad business!
Didn't realize that anyone held a patent on a round bushing... sheesh.
The window that these bushings swing in is also a factor for how much actual advance you end up with. They aren't all the same size, but, a 10 will get you real close. Just as a 14 will as well. The difference in a 10 and 14* bushing is ~.013". For every .001 in diameter the timing change is ~.15 degrees... are we really going to worry about .0001" or .015 degree timing tolerances??? REALLY??? If you can time your car to .15 degree accuracy, I'll give you a goldstar, at .015 you need to be a rocket scientist. :) Hunting flies with a sledgehammer comes to mind.
Not as though he was the only person to ever make these! I was making these with a hillbilly lathe (drill and file held in a vise). Mine aren't made with a file anymore and they are a bunch less money than than any of the vendors on Ebay when I have them. You don't have to take a file to the sides of mine like you may have to with the fbo unit.