Patent No 1700066 - Pyrex radio freq insulators
By John Graham; posted December 30, 2003
View Original: Click to zoom, then click to magnify (428 x 1055) 307KB
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Found these in an antique shop yesterday. One has a brass screw on top and one has a brass nut. Read about the patent at http://www.nia.org/timeline/text/1700066.htm |