All of our products meet ASTM specification E438, Type 1, Class A "Standard Specification for Glasses in Laboratory Apparatus." This borosilicate glass: Pyrex 7740, Kimax KG-33, or Schott Duran, all of which are functionally equivalent. The characteristics of this glass is described below:

Annealing Point: 560^oC
Softening Point: 820^o C
Linear Coefficient of Expansion: 32 x 10^-7 /^oC