The starting point is a clear borosilicate 3.3 glass bottle. The bottle then undergoes a unique ion diffusion process, creating an amber layer on the glass bottle with good chemical durability.The amber DURAN meets the requirements of USP <671> and Eur.Ph. 3.2.1. for protection against ultraviolet (UV) light. KIMBLE RAY-SORB meets the requirements of USP <671> EP 3.2.1. and JP 7.01 Section 5 for protection against UV light.