The Seachem Bottle Adapter Sm for 50-500ml bottles allows you to seamlessly connect dosing pump tubing to any Seachem additives bottles ranging from 50 mL–500ml and many other common supplement bottles (with 24 mm opening) on the market. Fits tubing sizes up to OD 0.192 inches/4.88 mm. Simply insert a plug into the bottle neck of your supplement of choice, then insert tubing into its opening. Once inserted, this connection will also help to prevent spillage in the event of a container tipping over. Be certain that the tubing runs to the bottom of the bottle.