You can use a penny to determine the size bowl you need for your bong.

Place the penny into the downstem and depending on how deep it sinks in, you will know what size bowl you need.

14MM - If the penny goes about 1/4 of the way in, that means you need a 14mm bowl.

THIS IS THE MOST COMMON SIZE

18MM - If the penny goes in halfway, then you will need an 18mm bowl.

10MM - If the penny barely goes in, then you need a 10mm bowl. We do not offer a 10mm size at this time.