Our Hydro Bubbler Glass Replacement is designed to fit our Hydro Bubbler for Cartridges which is designed to fit any 510 thread cartridge. Although the Hydro Bubbler for Cartridges already includes 1 glass bubbler, we have replacements available in the event your current glass bubbler breaks or stops working. The glass bubbler is what holds the vapor that you inhale the distillate or product from.