Bong Bowls - Dry Herb Bowl. Bong bowls are a removable slide that attaches to a bong and hold the dry herb. Bowl pieces generally comes in three sizes 14mm,18mm and 9mm (Slider Bowl). Whether you need a replacement slide or just want to cool bowl piece to add some life to your bong, you will surely find something that fits your needs. Hemp Roots stocks a variety of different herb bowls and attachements to fit your needs.