Just Sharing Some Precancels

There's lots of info here about precancels. I don't collect them myself (can't get into the minutiae) and I usually sell or trade them. But I have a couple of (I think) interesting examples to share.

First, a precancel in action. I usually just see them off paper, so this was different for me. No cancel - of course.




A Canadian example. George V front and back. An unused precancel, isn't that an oxymoron?

I have been putting aside all the ones I find with almost-complete gum on the back. I can't be sure whether they are actually "mint" but since I don't collect mint I thought someone else might appreciate them more.

Does anyone know if people collect them? Or am I just wasting my effort by isolating them?

I'm not positive on this but that bottom one looks like it could be a contender for one of those bar cancellations or a P.O. control stamp?