I guess around 1963, Rawlings introduced the flex-o-matic heel design in their gloves and mitts. This catchers mitt with the flex-o-matic palm that just closed on ebay looks particularly funky to me. It is a "Dick Bartell" model
Below is a Rawlings HOH on the right and a Spalding multi-flex-pad on the left.
Below is a 1966 Rawlings catalog with a few different mitt designs Although I am not a fan of the flex-o-matic palm, the Tony Kubek model below with the X web is pretty cool looking as is the Wilson Ron Santo glove with a flex-o-matic heel variation with lacing going up the thumb and pinky. Prety wild. I think Joe introduced the Santo glove a couple years back.