Includes over 100 Foam Security Seals / Tamper Proof Bottle Liners, for Sunscreen Flasks and all other similar discreet bottles for cruise smuggling booze. Diameter of 21mm (about the size of a US Penny, for reference). Made of high quality pressure sensitive polystyrene foam. Simply place the seals into the bottle cap with the writing side facing up towards the top of the cap. Then screw the cap on to the bottle, and the pressure will activate the adhesive, causing the seals to stay in place. No more anxiety about being caught with your hidden flasks with this extra layer of security and stealth!