Question about old style Arca Swiss rail

[Michael_4514]

I'm selling one of my older Arcas, and a prospective buyer has asked me what the function of the knobs on the vertical side of the rail is (see attached picture). The knobs are attached to a bolt that goes straight through the rail where it is fastened with a threaded round nut. The diameter of the bold is just under 3/8, probably whatever the closest standard metric size is. There are four on the rail.

I've done a pretty thorough google search and looked at hundreds of photos of Arca cameras and rails, and I don't find a single picture that shows these bolts serving any purpose.

I'm sure the answer is pretty obvious, but I just can't figure it out.

Thanks,

Mike

[dave_whatever]

You undo the knobs and the top part of the rail can slide or be replaced/removed, or a split rail used (i.e. to get extra extension).

[Michael_4514]

Thanks Dave,

That was my initial thought, but the rail seemed to be a single piece. Until I actually loosened the bolts and lo and behold. That's how well machined these parts are.

Mike