What is this band sight from. It fits a mauser barrel perfectly.

The tall blades are the right profile but a bit too thin. slot is .06. cross holes don't line up.

It's a military band that someone cut the dovetail off and slotted it.
Maybe.

Looks like maybe an old Pacific Gunsite Co banded front ramp with the back end of the ramp portion cut off.
Then the remaining bloc given a slant and fine line file effect