DURAN® HPLC reservoir bottle, clear, conical base, GL 45 Boro 3.3 Borosilicate glass 3.3 has a very good chemical resistance, virtual inert behavior, a high maximum usage temperature, high light transparency and minimal thermal expansion. Borosilicate glass 3.3 has a linear coefficient of expansion of 3.3 × 10−6 K−1 at