Our glass pocket flasks are made of thick quality glass, so they are durable to withstand normal wear and tear. The plastic caps fit securely atop the bottle, which keeps these bottles airtight and leakproof. Tight seals ensure the contents inside remain as fresh as the day you bottled them. These glass flasks are eco-friendly and reusable. For more than just liquor, these glass flasks are widely used to use to store water, syrup, sauces, oils, marinades, and more.