Certified Glass Inserts – Certified Vials | Sigma-Aldrich. Inserts for 12 x 32 mm large opening vials. Product #. Description. Add to Cart. 29435-U. Certified glass inserts for 12 x 32 mm, large opening vials volume 0.2 mL, clear glass insert (with plastic bottom spring), O.D. × H 6 mm × 29 mm, pkg of 100 ea. pricing. 29436-U. VIALKY