These look like the bases used on RCA "Special Red" Series premium tubes from the '50s-'60s. What a great idea! Outside diameter 1.304", inside diameter 1.190", height .879". Nickel plated brass pins. Brand New production from China. Great for making your own tube adapters, test jigs, replacing broken bases on old tubes. This tube base fits well with the QQQ #88297 and the #8572 octal tops that we sell.