Designed to fit glass bottles only. The eyedropper is incorporated into a threaded cap which can be screwed onto the top of the bottle. Please note, these droppers do not fit most LorAnn products. Only the following products are packaged in a 4-ounce glass bottle: 4-ounce Super Strength Flavors: Cinnamon, Lemon, Wintergreen, Orange, Peppermint, Clove, Spearmint, Anise, Lime, Sassafras, Key Lime, Tangerine, Nutmeg, Almond, Ginger, Teaberry, Grapefruit, and Lemonade. 4-ounce Almond Bakery Emulsion is packaged in a glass bottle (all other bakery emulsions are in plastic). All 4-ounce size Essential Oils are packaged in glass bottles.