What are these for please ?

[rustyric]

Made by Bowers and in an imperial size.

[lptools]

Hello, Rustyric. You have a set of Counterbores, the pilot (opposite the shank end) enters a pre-drilled hole . The larger diameter cutter cuts a larger hole so the head of the bolt bolt or capscrew ends up flush, or slightly below the surface. . Picture a set of vise jaws, and the way the screws are inset, most likely a counterbored hole. I am not familiar with the manufacturer. Regards, Lou

[rustyric]

Thank you for your reply

[Plyerman]

Yep, what Lou said. Here's a longer-style counterbore tool, which just got done counterboring a hole.