These replacement screw caps are designed to fit perfectly inside the Oddballs LED balls and Oddballs Glow Fade poi. They are ideal for those who have lost their original screw caps, allowing them to continue using their LED balls and poi without interruption. The screw caps are easy to install, simply screw them into place and you're ready to go. They are also a great backup to have on hand for when you need them. With these replacement screw caps, you'll never have to worry about losing your original caps again.