Technical Ansen spinner center caps

I just picked up a pair of Ansen caps that have the three prong spinner centers. The centers knock off and have the word Ansen on them. They are plastic.
I haven't seen any of these before and was wondering if anyone can tell me what years they were on the market, and which Ansen wheels they were used with.
Any help appreciated.

 

Those were available in the early '70s, and were sold as a stand-alone accessory. They would fit just about any aftermarket wheel that used five screws to attach the center cap. I had a set, and used them on some ETs and Americans both.

 

Thanks for the information. They probably will end up on the back of my Studebaker.