[TowerTalk] B&W Center Insulator for dipoles

[Al_N6TA at comcast.net]

One of my junk drawers just coughed up a B&W cast aluminum center insulator for dipoles.  It is a two piece clamshell design that is really heavy duty with eye bolts, ceramic insulators, gaskets and seems to want to clamp to the coax feedline.
My question to the old timers out there is why is hole for the coax 9/16 " diameter, much too large for RG-8 type coax?  Am I missing a part that is a gasket of some kind that would make the RG-8 fit?  

If this B&W unit is used correctly, I seems like it could take a LOT of tension and weight of coax hanging a long way down.  I plan to raise my 80 M dipole to heights it has never seen before!

Tnx
Al
N6TA