These are to fit 10mm diameter bars or rods.
They can be used to fix items to the bar where a boss can be screwed to the item in question.
They are 2-part fixings -
The inner brass boss can be screwed to the item you wish to support
The outer part fixes to the boss using a grub screw and slides on to the bar. It is secured in place on the bar by tightening a grub screw.
Fixings are in satin anodised aluminium, with a brass boss.