3" (76mm) Diameter back to back pair of clips | Aura Sign Shop
Prest-On 1/2in Insta-back Drywall Fasteners
Back Picture Frame Hardware | Picture Frame Back Clips | Metal Photo Mirror Frame - Picture Hangers - Aliexpress
Amazon.com : 25 Pack - Premium Name Tag/ID Badge Holder Spring Clips with Metal Bulldog Clasp & Square Adhesive Back - for Badges, Buttons, and Nametags by Specialist ID : Office Products
road and traffic sign clips back to back
Back To Back Sign Clips for Post Mount Signs - 76/89/114mm
1/2 in. Corner-Back Drywall Back-up Clips (50-Pack) 4015 - The Home Depot