Marijuana Glass Bongs are smoke filtration devices generally used for smoking cannabis, tobacco, or other herbal substances. A bong is similar to a pipe, only it has a water-chamber through which cannabis smoke passes prior to inhalation. Almost any bong can be converted to a dab rig by adding a glass banger instead of a classic herb bowl. Users fill the bong with water, sometimes also adding ice in order to cool the smoke. This cooling effect reduces the discomfort caused by the heat of the smoke. The bowl and stem assembly of most bongs is removed briefly after the cannabis is burned, allowing clean air to circulate and clear the smoke chamber, ensuring no smoke dissipates without being properly consumed