These are Pressure Sensitive seals (PS Foam Liner) that fit inside the lid of your jar, and when properly applied, will stay attached to the jar until they are peeled off. The seals have "Sealed for your protection" written on them., so that your customers know that you care about your product quality. 100 PCS OF 22mm Press Seal Cap Liners Foam Sealed for Your Protection Fit jars or bottles with a 22mm opening. Tips on using the cap liners: ? PS lines are designed to be used as an inner seal to seal solid products, such as dry foods and pharmaceuticals work with thick liquids such as creams and sauces ? These liners are NOT recommended for watery liquids like juices especially essential oils ? Clean the lip of the container with alcohol to ensure there is no oily residue that will prevent the seals from sticking. ? To use the seals, place them inside the lid with the white side facing out. ? Screw the lid on as tightly as you possibly can, and let the container sit for at least 30 min. Common mistakes to avoid ? Lip of the jar is not clean. ? Seal facing the wrong direction when applying ? Not enough pressure is applied when installing the seal. ? Not waiting enough time before removing lid. ? Over filling containers is another common cause for leakage.