The one ounce (30 ml) Roll-On Bottle Plastic Roller Ball is the perfect choice for sealing single bottles of liquid. Many clients purchase our Roll-On Bottle tops to place on top of small singles that they are pulling out of storage for distribution or retail purposes. Each plastic Roll-on Bottle Roller Ball is made out of a firm plastic material that offers reliability while still maintaining its flexibility so that the ball rolls easily. Perfect for liquids and semi-soft materials, the Roll-on Bottle Roller Ball seals any 30 ml bottle easily with a screw indentation. Seals any 30 ml "Roll-On" bottle.