Stainless steel metal roller ball inserts that fit your 5ml and 15ml essential oil bottles! Now, you can turn your Young Living bottles into roller bottles with these stainless steel rollerballs. Don't throw away your old EO bottles, reuse them! You can use your used oil bottles to make your favorite essential oil roller blend. Turn them into roller bottles and share them with your family and friends! To use simply place the rollerball in the bottle opening and press firmly until it snaps in place. Then add the cap and you are going to go!