Pro Angler cradles...does anyone have these?

[BrokeLoser]

I'm considering these for my trailer but wanted to know:
How they mount?
And what kind of mounting hardware they come with?

http://www.jerseypaddler.com/images/products/hob_cradle_proangler.jpg

[Iceman]

They bolt right up to Hobie's Trailer with a track bolt. The pads go on and cover the hardware. You may need extra hardware to make em work on anything else.

You can see the channel that the bolt heads slips into on the cross bar.

http://www.hobieco.com/linked_images/kayak/38652000.jpg

[BrokeLoser]

They bolt right up to Hobie's Trailer with a track bolt. The pads go on and cover the hardware. You may need extra hardware to make em work on anything else.

You can see the channel that the bolt heads slips into on the cross bar.

I haul two yaks on a converted jet ski trailer so I'm trying to figure out how much of a hassle it would be to try and make them work.
Do you know what size the track bolt is or what size the mounting hole is through the fiberglass cradles?

Thanks Ice!