Here's a line-up of three Pyrex embossed radio strain insulators. The first one on the top is from France and I'm estimating its age is circa 1940 or later. The middle one is a vintage "Societe Le Pyrex" (marked on the box [id=170606378]) from France in circa 1925 and came in a New Old Stock (NOS) box. Note it is the smaller of the three and its shape is different then the other two. The bottom is a faintly script style embossed Pyrex (side 1) and JP (very faint only partially readable) for Jobling-Purse (owner James Jobling and nephew team) and is circa 1930-38 and made in England. For a better view of the JP (as found on another example) [id=170603865].