Yeah, it's been believed here that Black Widow was the release they switched to these slips with flaps, being a more popular release, but actually I think this is the first one, half a year before Widow.
I just wasn't interested in these animation titles and weren't checking up on them.
At least this still had a booklet. Later they switched to 3 postcards, now just 2, with one repeating the cover. Why do they bother at all then.