Unfortunately the yellow backs in the regular 68 set differ some by series and some later series have back similar to the MB cards and are often mistakenly offered for sale as MB cards, including the Mantle. When searching for them have the official CL handy . See the article referenced in the first post in this old thread
https://r.search.yahoo.com/_ylt=AwrE...7Q3CL5KFxgf6M-