First hydrolytic, Class A, Type N51A, Pharmaceutical Grade, Borosilicate Glass, amberized. Amber vials are often used for light sensitive compounds and are considered low actinic. These Storage Vials have 66x18.5mm outer dimensions and a total fill volume of 12ml and can be used for long term storage with a proper cap. Use with Caps that have 15-425 or ND15 screw threads, sold separately.