The GRAV Hammer Bubbler is a compact 4" glass water pipe that delivers the smooth hits of a bong with a palm-sized hammer design. Made of high grade borosilicate glass, the Hammer Bubbler displays true flavors with a thermal-resistant airpath. A cross-cut downstem diffuses smoke into the water chamber to purify and moisturize hits, while a roll-stop allows you to set the Hammer Bubbler down in between hits without spilling the bowl. This 5 pack of GRAV Hammer Bubblers requires no accessories. These bubbler pipes function best with 0.5" of water.