i really can't remember as it came unspecified. but the silica was thin, 1 or 1.5 mm, the wire also was thin, a bit less then 0.2 mm (0.32 awg). i prefer 1.5 - 2 mm silica. i guess you can run any thickness of wire on the ERA, depending on what voltage you want to use. haven't tried 0.28 awg...