These PYREX® capillary melting point tubes are made from No. 7740 glass.

For use with thermometers calibrated for 76 mm immersion Borosilicate glass, thin wall, with one end sealed Length is 110 mm Inside diameter 0.9 to 1.1 mm   and wall thickness approximately 0.25 mm; complies with requirements given in the United States Pharmacopoeia.