If you have a Bong, then you need Slides. It is always good to have extras. Before Glass on Glass, Bong Slides employed a rubber O-ring to seal, and they slid in to a down stem. Lots off these old school bongs are still in use today. These “pull” slides come in two sizes, 9mm and 12mm. Glass on Glass came around and became the preferred design as the slide sealed without the O-ring.The Glass on Glass slide has a ground surface (looks frosted) that naturally seals against the ground surface of the joint on the down stem. This page contains all of our Slides. Use the drop down menu to filter the slides to your needs. Glass on Glass or Pull Slides. And then filter according to size.Glass on Glass in 14mm or 18mm. Pull Slides in 9mm or 12mm.