Organic chemistry glassware. This thermometer adapter uses a Nylon® compression cap and Viton® O-ring to form a vacuum tight seal. The cap accommodates 5.0 mm to 7.5 mm outer diameter thermometers. A ground glass joint allows pieces to be assembled leak-free without stoppers. Supplied with one Nylon® cap and one Viton® O-ring. Instructions and illustrations for setting up organic glassware for a variety of procedures, such as reflux and simple vs. fractional distillation, are available in the PDF above under Resources.