Blister packaging is most commonly used in the pharmaceutical industry. This is the familiar sheet packaging of pill or capsule medications in individual “blisters”. Pharmaceutical grade blister packs must be produced in an ISO certified clean room. This ensures that the products contained within the blisters are sterile. It is also used to package multiple small items, for instance thumbtacks, and medical devices. Hinged blisters are known as “clam shell packages”. This packaging option is commonly used as a security feature and is sealed by heat crimping the edges. This makes the packaging air tight and water resistant. Another style of clam shell packages are used as resealable packages. This style is often seen in the produce section of grocery stores containing, strawberries, blueberries, tomatoes, etc.