The NJS Jaguar post by Nitto is bomb proof. If an asteroid were to collide with the earth, all that would be left would be cockroaches and a pile of NJS Jaguars. It has a two bolt clamp so like the S83 the Jaguar isn't going to slip even with a saddle bag hanging off the back.
You will see the Jaguar has two different widths of guts. 9 times out of 10 you are going to want the 44mm. If you needed the 30mm, its very likely you would know that you need it. The 30mm is typically for narrow NJS track saddles.
Made in Japan out of Aluminum Alloy
Diameter- 26.8 or 27.2
Two Bolt Design
Rail Clamp Width (Center-Center)- 30mm (Narrower than most. Typically NJS Specific.) or 44mm (This is going to be what you need 99.99% of the time.)
Length Above Minimum Insertion Line- 135mm