I was really hoping this would save time but I did was disappointed. The part that slides over the drill bit was clogged with chips at each hole and I had to remove them manually to get the mechanism working again. The ring/guide is exactly .375"(3/8) . It would be nice if it was a slightly smaller size to make it easier to slide into the holes in the template. zero spacing. I'll save these details in case I need to add shelves to an existing cabinet, but to make new cabinets I go back to the drill press like I always did.