This is an IKEA Skådis hanger that provides a Tentacle System base.
The Tentacle System allows you to create ad hoc stands and holders using a variety of connectors and holders. This part lets you attach those ad hoc stands to a Skådis pegboard.
You can learn all about the Tentacle System here: https://3ddoodle.com/tentacle-system/
The author marked this model as their own original creation.