John23883
I definitely remember those but for the life of me I am not sure which mast. It would have been one of three, Z Spar (US Spar now), Dwyer aluminum masts or Charleston Spars (possibly Kenyon Isomat) depending on the age of the boat. If you will look on the side of your mast, you might find the manufacturer's name.
However, it is simple sail feed stop to keep the sail slides of the mainsail from falling out. There are other sail stops that would work but not sure if those which you pictured are still available. First can you identify the mast by the manufacturer sticker on the side of the mast.
I would address this in the small boat section for a quicker respone