Don's bulbs rare light bulbs and lamps glossary of terms definition of: /FR What is special name suffix "/FR"? This special name encoding reference means: Frosted glass. Typically applied to outside of glass, but frost coat could be applied to bulb inside glass. Also see /IF and /CL references for this page: /FR, FROSTED GLASS, FROSTED references to this page: /C, /HF, /IF, /LF, ENCODINGS PHILIPS OLD BULBS