2 mL Crimp/Snap Top Vials & Crimp/Snap Caps Aijiren 2 mL snap top vials are constructed from Type 1 borosilicate glass, with low metal content, to protect your sample from destabilizing or leaching. The associated 11/12 mm snap caps come with your choice of cap septa constructed from either PTFE/silicone or natural red rubber.