A bong with double filtration and a bigger tube where the smoke is concentrated is a type of water pipe that is designed to provide an even smoother smoking experience.
This type of bong typically has two chambers or percolators, each filled with water to filter the smoke. The first chamber, which is typically located at the bottom of the bong, is where the smoke is initially filtered. The second chamber is often located above the first chamber, and it contains a percolator with multiple holes or slits to further filter and diffuse the smoke.
The bigger tube where the smoke is concentrated, also known as the "neck," is located above the second chamber and is usually wider in diameter than the rest of the bong. This allows for a larger volume of smoke to be inhaled at once, which can result in a more potent and intense smoking experience.