Well, it is a shape of the grip from the back view
1950s through Mid1960 era on N frames grips mainly 44 magnums I’m just giving you the minor details. I’m sure somebody will come along and get really technical.
They are extremely rare most people that have them will not sell them. You do see them occasionally on eBay if they are in really good condition, they will bring $800 for the grips alone.
Tom