I bought a USB charging jack designed for a car's dashboard, and designed to fit in the same size hole as a cigarette lighter.
Many versions for sale. This one, no more expensive than the others, came with a hole saw for 1 1/16", a size I don't have**. The hole saw has the shank, the center drill bit, an allen wrench, the hole saw itself, and a spring!!!
A tapered coil spring whose small diameter just fits the bit. Is that a coincidence? What is the point of the spring? I've used a hole saw before and didnt' feel a need for a spring. Is it to force out the hole after it's been cut? Have you seen this before?
**Last time, I think I used a 1" hole saw and a reamer to make the hole bigger. Now I can't find my reamer and NO ONE sells a reamer that big. How can that be? I don't remember where I bougth the one I have, but I think it was a yard sale or hamfest, not retail. It's metal with a yellowish top and an unevenly applied vinyl overlay for the top. Where can I get another one?