Metal plate scan hook extends above its Flat Bar to better show wares in a multi-tier display.  I have seen extended height hooks like this most frequently in bar merchandiser applications.

For a summary Pinterest Board “extends above” fixtures see…
“Periscope Hooks and Fixtures in Retail“

To research individual “extends above” discussions see…
“Stable-Base Periscope Hook“
“Periscope Bar Merchandiser“
“Periscope Gift Card Hook“
“Periscope Hooks Expand Display“
“Periscope Scan Hook.”
“Periscope Single Prong Hook”
“Periscope Loop Hook“
“Periscope Hook Pimple“
“One-for-All and All-for-One Ballstops”

For all Pinterest Board summaries of extenders see…
“Extenders: Vertical Surface Display“
“Extenders: Horizontal Shelf Edge Display“
“Extenders: Periscope Hooks and Fixtures“

For line item “extender“ concepts SEE…
“Traditional Pegboard Extender”
“Modern Pegboard Extender”
“Wire Basket Extender”
“Overhead Hook Merchandising”
“Pegboard Extender Naked”
“Periscope Hooks Expand Display“

Also browse shelf edge extenders at…
“Single Item Shelf-Edge Extender”
“Shelf Extender is Bottom Mount“
“Shelf Edge Shoe Extension“