I started collecting Pyrex power & telephone insulators back in the mid 1970's when I purchased a carnival Pyrex 353 at a flea market in Utah. Immediately I wanted to specialize in Pyrex. My latest addition is a Pyrex 553, the large insulator next to the 701. There are some Pyrex radio strains in the collection, but I had no room on the display shelf for them. I hope they didn't feel left out, poor things.