those look like they are made to drill pocket holes for screws. Like a Kreg type pocket hole drilling machine type thing(although the Kreg system uses a step bit)
I used to use one in a shop for assembling face frames, now I use something a bit different.
I bet you could find them as replacement bits for the boring machine that is meant to drill the pocket holes, there are many varieties, makes and models.
I see you found it and the one you need is on sale, nevermind.