9mm 2ml Short Tread Glass HPLC Autosampler Vials have two different materials, one is borosilicate glass, and the other is imported first-grade hydrolytic glass, which can meet the different needs of customers; The 2mL Amber Screw Top Autosampler Vials are made from high-quality amber glass, providing excellent protection against light and UV radiation. The amber color helps to preserve the integrity of light-sensitive samples during storage or analysis. Amber glass vials are perfect for storing samples that are sensitive to light exposure. Clear glass vials are great for testing the solubility or dispersibility of materials, allowing you an unhindered view of the solution.