I picked this up in an antiques mall along with a couple of dozen insulators. It's a light globe embossed (F-Top) REYNOLDS/ELEC. CO. CHICAGO (R-Top) PAT 10/29/12 [Note backwards "9"]. Here is the patent: https://patents.google.com/patent/US1042979A/en. The top is threaded to screw into the light fixture; the inside is hobbled like a Coke bottle; and the color is Emerald Green. It's mint. See [id=610678853] for sales info.