Potassium tetraborate tetrahydrate, min. 99.5 %, cryst., Molar mass (M) 305,50 g/mol, Density (D) 1,911 g/cm³, Boiling point (bp) 850 °C, CAS No. [12045-78-2], EG-Nr. 215-575-5, Empirical formula K2B4O7 · 4 H2O