Turns Bubble Bottle into No-Spill! No Spill Bottle Caps are easy to use andFits Most Popular Size Bottles. Easy to use: "-Remove foil from any bubblesolution bottle and discard.", "-Place Bubble Cap on top of bubble solutionbottle opening."(note: make sure the fit is snug), "-Use wand provided to blowbubbles.", "To clean Bubble cap, remove from bottle of bubbles and rinse withwarm water." Notes to Parents: -fits most bottles of bubbles.", "-Does not fitall sizes and shape bottle of bubbles.:, "-Works best with 4 oz and 8 ozbottle of bubbles."