The small Grav Hammer Bubbler is 3" tall and made on 25mm tubing. Its fission downstem diffuses smoke through water, and its feet stabilize the bubbler between uses. No accessories are necessary for using this bubbler, and it functions best with approximately 0.5" of water.The small Grav Hammer Bubbler is 3" tall and made on 25mm tubing. Its fission downstem diffuses smoke through water, and its feet stabilize the bubbler between uses. No accessories are necessary for using this bubbler, and it functions best with approximately 0.5" of water.