Johnny Sain demonstrates how to use a device to improve a person's pitching grips. Sain sold the product himself; this is a postcard and ordering information is on the back:
While it looks like a baseball that's been placed on an awl, it was available for purchase ($5.25 including shipping) to anybody who wanted one.
This postcard has been approximated as being issued in 1962. Sain served as the Yankees' pitching coach under Ralph Houk from 1961-'63, so this postcard was definitely from that time frame, and the lack of a ZIP code in the address (introduced in 1963) indicates that as well. In the book Ball Four, Jim Bouton explains that Sain was a great coach when it came to the mechanics of pitching, so maybe he was on to something when it came to this.
