If it doesn't have a bowl, it's not a bong. This is where your precious weed is placed before being lit and ripped! Being a small piece that needs to be constantly handled when operating a bong, it's important to make sure it does not break. That is what the 3 bubbles surrounding this bowl is for, they prevent your bowl from rolling to its doom. They are also have a second use, providing a better grip anytime you handle the bowl.
Joint: 14mm Male