This product is a 20 mm gray chlorobutyl rubber stopper designed for use as a sterile, airtight seal on glass serum vials or bottles with a 20 mm crimp-finish neck. The snap-on (straight-out) design ensures secure closure while facilitating easy vial access during pharmaceutical compounding or laboratory procedures. Manufactured from chlorobutyl rubber, these stoppers offer excellent chemical resistance, durability, and low gas permeability, maintaining vial integrity and product stability. Supplied in a bulk quantity of 1,000 pieces, they are ideal for high-volume clinical, pharmaceutical, or research settings requiring reliable and consistent vial sealing solutions.