Not all .22 magazines were stamped with the ".22", however they will have the lips up front cut straight so the inside edge is flat. The lips on this mag seem to be a bit off - right side seems to be rounded and the left side almost looks like the end of the lip has broken off. The follower though is real and the large hole at the base end is for the empty case to fall into.
Let us know if there is any mark on the side.