Can this be put on gutter that is not under shingles?

I think that if the front edge of the guard is screwed to the front edge of the gutter (as described in some of the reviews)it will stay in place on top of a gutter that isn't under shingles. Because the guard is made of steel it is very stiff. My assumption here is that your gutter is mounted some distance below the roof line. You could buy one section and try it.

The guard stays in place by both the curved edge that locks onto the gutter and laying under the shingles or in my case the drip edge. There is nothing to hold the guard in-place on the shingle side other than these two methods.

No, this product cannot be used on a gutter that is not under shingles