These were in a batch of hobby shop items I puchased. Not sure if they have ever been used. They appear to have had an electric starter applied but the back plates and spinners have never been drilled, at least according to the directions. Best guess is these were made in the early to mid 70's. New Tru-Turn spinners this size run 250-275 dollars. These look like P-51 style spinners. I will never build anything needing something this big.