Grav Labs 6' Upright Bubbler - Clear - 32mm Glass The small GRAV Upright Bubbler is 6" tall and made on 32mm tubing. Its fission downstem diffuses smoke through water and is fixed inside the bubbler to prevent damage. Its angled mouthpiece acts as a splashguard, and its lip wrap is tooled for comfort. No accessories are necessary for using this bubbler, and it works best with approximately 1.5" of water.