Clear plastic butterfly hooks as seen on a custom point-of-purchase display. But this same style of hook that occupies but one-column-width of holes rather than the standard two-in-width are available for regular pegboard too. Their normal purpose is to allow high-density, shoulder-to-shoulder display of narrow product (Tooth brushes? Bolo ties? String bikinis? Travel size packs of Pipe Cleaners?). Here they may be in use as a design as well a cost-saving strategy … though make sure you bid the job both ways. I suggest that two-column-width plastic hooks are manufactured in far greater quantity and at lower cost than less-common, one-column-width hooks which use marginally less material. If you know which is cheaper in quantity, please post the answer as a comment.

For more on One Lug / One Hole Hooks VISIT…
Perfect Use of One-Hole Hooks
One-Hole Hooks Compared” and
One-Hole Hooks on Display

For other other density-increasing arrangements SEE…
Hook Mis-align Increases Sales
Hook Stagger Violates Convention” and
Erratic Hooks Tighten Display.”

For narrow items in retail SEE…
Slim Jim on a Pegboard Hook
Sasquatch vs Slim Jim

For vertical label holders as a space saving device SEE…
Rotated Toothbrush Label Holders” and less well-done
B/P Anchors Toothbrushes
Label Orientation Alternates

Also compare label holder size and use at…
Label Size vs Display Density
Rulers Sold On Hooks
Short Sheeted 3/4″ Deep Label Holders
Buy-One Get-One Flip-Front Selling Tool
How to Make a Flip Front Sign Holder
Narrow vs. Wide Label Holders.”