The vials use certified crimp caps with PTFE/silicone septa to ensure your SVC211C, 2ml Clear vial, 12×32mm, Crimp top(11 mm mouth), graduated with 11MM POLY CRIMP SEAL – Chemglass CV-1168-1232 : Vial, Standard Opening Crimp Top, Clear, 2.0mL, 12 x 32mm, 11mm Crimp Poly Crimp™ Seal, 11mm, Clear Cap, PTFE/Silicone Septum with Slit.