Lengths Available: 3/4”, 1-1/4”, 2”, 3", 4”, and 12 " are the typical sizes. In general the "length" is measured below the collar. Allow for some fluctuation. Tube outside diameter is approximately 6 to 7 mm (about 3/16+ inches). Flared collar approximately 10 mm (about 3/8+ inches) in diameter. Tip extends about 5 mm (about 4/16 inches) above flare. Measurements have some variations. Materials Used: "Pyrex" and "Instrumentation" or "Lab Glass"; thermally stable types of glass. Fiberglass wick SKU to use is #1284 or folded #`1376.