Pyrex clear glass insulator with smooth drip skirt. It is 4" high by 2 1/2" diameter at the base. It has the Pyrex name with "T.M.REG.US.PAT.OFF." under it. On the back is "Made in USA" under that is "Pat.Appd.for". It has a faint circle with a Capital 'H' and an 'S' inside. It is very clear glass with a very small chip at the top of the dome. More like a scratch.