Specifications. Vial, headspace, certified, crimp, clear, flat bottom, 20 mL, 100/pk. Vial size: 22.75 x 75 mm (20 mm cap) Aijiren headspace vials are constructed from type 33 and type 51 COE borosilicate glass, with low metal content, to protect your sample from destablizing or leaching. Using Aijiren vials can protect your sample while