2mL, 12x32mm standard opening vials. 8-425 thread finish. Smaller opening (5mm ID) has less solvent contact with septum. Superior quality 1st hydrolytic class glass (Type 1) in clear and amber. Meets all requirements of Pharm. US, EU, JPN. Freezes well. Compatible with standard GC and HPLC autosamplers, as well as older autosamplers.