Tree stand umbrella Help

I have a tree stand umbrella (I think it's an Altan) canopy is round, attaches to the tree via a plastic bracket with a strap that the metal arm slides into. It can also be used as a blind.

When setting up at the end of October I somehow managed to lose the black metal arm... :confused:

I'm looking to make a new one but need some help determining the length of the arm. If anyone has one and can tell me the length of the straight part of the arm, from the bend at the tree end to the shaft that points up (where the umbrella slides on) it would be a big help.

10 inches
Glen

Thanks Glen, that's just what I needed, I was off by 2".
Much appreciated.