Aijiren 0.25 mL Vial Inserts, Glass, Flat Base, 100 . 0.25mL Vial Inserts Glass Flat Bottom Clear Insert Tube for 8-425 Vials, 100 pcs/pk Material: USP Type 1, 68 Borosilicate Expansion, 1st Hydrolytic, Clear Glass These vial inserts are perfect for limited volume analysis and to reduce solvent waste.