The snap top caps are a great choice for containing products that need to be dispensed in controlled doses. To dispense the product the hinged cap is flipped up, the product is dispensed, and then the cap is re-sealed by simply pressing the cap back onto the beaded finish. This 38-400 black polypropylene (PP) plastic flip top dispensing cap has wide mouth opening, crab claw sealing mechanism and smooth outside round skirt. This cap features a pressure-sensitive foam liner PS113. The liner is designed to be used as an inner seal for dry products. These snap top caps with wide mouth are great for dispensing pills and tablets, without contaminating the entire contents Note: Pressure sensitive liners provide an extra level of protection in that it actually creates a seal that sticks to the rim of the bottle.