As far as i know, the Provid has the same centerpost as the Archer and presumably the same threads on the folding part of the centerpost. For the Archer, i know of two off the shelf mods. One from MK-V, and one from Hofmann Teknik in sweden. Another option which i have done to my Archer, is to use a combination of off the shelf 15mm rods and clamps, and a couple of custom machined pieces to make it fit together. My rig is a lot more compact than a standard Archer or Provid now when i want it to. It can also expand to spread the masses for more inertia when that is needed.