This is a Vintage Keychain with a movable, dancing, photo For Sale

These keychains were in my Dads desk drawer for quite some time before he passed away in the early 1970's. The vintage would be from the 1960's or possibly the 1950's. I listed the keychain as pre-owned, but I do not think they were ever used.
Very Good Condition As Shown, Please see photos for details. The plastic portion measures 1 3/8" x 2".
The pictures are Black & White optical illusions with Flicker Dancing Pin-Up. When moved the ladies image dances! Rare vintage. One moving photo was attached.