I've got one inside one wall of my house. When I did the electrical rewiring of the house, I would stack two, even three, of them, to drill through firestops to run the light switch wiring. One trouble with that design is the set screws can work loose, releasing the bit, or, in my case, the bit and the first extension, which now reside somewhere in that wall, to be found by whoever (and it may be me) opens up the wall next.
Newer designs use spring-loaded collars, like Yankee screwdrivers - far superior.