We found four of these nailed just below the roofline on an old wooden building along the railroad. They're white glazed porcelain with 'Sears' and 'USA' embossed on one end. They are also threaded inside about halfway up from the base. Measure 1 1/2" tall x 1 1/8" dia. Were they a poor man's do it yourself home insulator available by mail order catalog?