Replace the little rubber piece on your downstem or bowl with the JBD Fix-It Kit. This pack of 3 O-rings and 2 Grommets is the perfect way to stay prepared and keep your seal airtight! Why does JBD use Rubber O-Ring? With functional glass, a perfect seal is everything. While "Glass on Glass" joints are made to fit the best they can, they just don't have the flexibility rubber has to create the ideal seal.