Night Riding -- Reflectors on Trees

I went night riding for the first time last night. I rode wooded
trails with which I was familiar. I was surprised to see that many
trees along the trail had tiny, bright reflectors (~1/4 inch in
diameter) attached to them! I had never noticed these in daylight.

On close inspection I found at least 2 types. One type seemed to
resemble a thumb tack, with the head of the tack being reflective. The
other type was more like a push pin with a bead for the head. The
design makes it visible from many directions.

I have been told that hunters use these for orientation. I would like
to add some of these to some of the more difficult un-blazed trails on
which I frequently get lost!

Are these reflectors commercially available (where?) or are they
"home-made"?

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