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Porcelain Fireplug Insulators

These unusual porcelain insulators are nicknamed for their unusual shape that resembles a fire hydrant.  These were patented in 1910 by Albert Stadermann, and can be found in several variations.  Two examples are shown below along with the patent image.

Here is the more common style marked UNIVERSAL

Here is a larger style with double grooves on each arm marked with the patent date.


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