CRL's 1-1/4" (32 mm) Square Standoff Cap Assemblies can be used with Square Bases or independently to attach panels or artwork to a wall. They are easily installed with the Square Standoff Bases due to our exclusive design. The secondary cap, with removable allen screw, has two flat sides which are used to secure the cap to the panel material. When firmly in place, the top cap is paced over the secondary cap, then aligned with the square base and held in position with undetectable double-sided tape. With this design there is no "adjustment" or "trial-and-error" required to line up the cap with the base. The Cap Assembly comes with a detachable 5/16"-18 x 1" Allen screw that requires a 5/8" (16 mm) hole for assembly.