Hex Key (Allen Wrench) tightened “pucks” form the mount for these Apparel Faceouts. The pucks can be slid along the runner and set at any height. Faceouts clip onto and cover the pucks. One assumes the puck’s Backplate can be rotated and removed from the slot, or additional pucks mounted as needed.

Compare directly to…
Round Faceout Fits Square Hole

For interesting alternatives see…
Bayonet Mount Outfits Acrylic
Bar Outfitted with Bayonet Mount
Bayonet Mount Hook
Bar Merchandiser Plugs-In
Large-Bore Plug-in Hook
Hidden Hex-Key Mount Faceout” (This Post)
Round Faceout Fits Square Hole

Moving farther afield browse…
Plug ‘N Play Jewelry Display
Wood Inlay as Point-of-Purchase Display
Basketball as a Seasonal Theme
Tree-Like Display Sports Metal Faceouts
Hat Ledge Plugs In
When to Use a Permanent Hook
Baseline Post for Plug-in Hooks
Plug-in and Pegboard Hooks Combine
Plug-in Hook of a Different Sort

For a takeoff on the Puck aspect see…
Hockey Pucks on Hooks