Rule-Joint Hinges

These solid brass hinges are widely used for drop-leaf tables., They perform the same basic function as a back-flap hinge, but one leaf is wider than

What kind of hinges are these?

Creating the Rule Joint - FineWoodworking

Making a Cedar Sofa Table - Australian Wood Review

Routing Mortises for Drop Leaf Hinges on a Rule Joint — Alabama Woodworker

Hinges

Routing a Rule Joint to Make a Drop Leaf Table

Drop Leaf Table Hinges, Specialty Hinges

Smooth Black Iron Rule Joint Stay

Rule-Joint Hinges - Lee Valley Tools

Concealed Door Hinge

Master the Classic Rule Joint • WoodArchivist

Rule Joint With The Stanley 55 Plane