The Allergen Detector can be used to check foods for the eight most common ingredients that cause allergic reactions. Simply hold the device close to the food and press the button. A light will appear if an allergen is detected and you can check the back of the device to see what it is. The Allergen Detector comes with a replaceable cartridge made out of biodegradable PLA plastic that contains a thin roll of film with drops of antibodies that react to food allergens. This handy new product can protect you against annoying and even life-endangering allergy attacks.