Thermometer holder, rubber. Organic chemistry glassware.Standard taper 19/22 mm joint size. Ground glass joints allow pieces to be assembled, leak-free, in minutes with no need for use of stoppers or other foreign connecting devices.Instructions and illustrations for setting up organic glassware for a variety of procedures, such as reflux, simple vs. fractional distillation, etc., may be obtained by requesting Flinn Scientific Publication No. 10876. Please call or e-mail us to obtain your complimentary copy.