Tubes are 2⅛" Pyrex Glass and are used with 1/8" thick wick. There is a small collar at the top to keep the flame off the lid and hold the tube in place in the hole of the lid. The collar is about 7/16" in diameter, just a fraction more than 3/8".
Wick is 1/8" EVERLASTING fiberglass, 6 -7" long, and never needs trimmed or replaced like cotton wicks do. Complete instructions included.
