Ship your liquids with confidence when you use Labelmaster's Polypropylene Caps with Teflon® Liners. Designed to fit a wide range of glass or poly bottles from 4 to 128 oz., these black caps can be used to contain analytical lab samples, high purity chemicals, strong acid solvents, environmental samples, pharmaceuticals and diagnostic reagents. You can rest assured knowing that your liquid shipments will arrive intact as we put our bottle caps through extensive testing to ensure tight seals and unrivaled durability.