A the bowl or slide of a waterpipe is the glass portion where you heat your tobacco, herbs or concentrates. Almost all waterpipe slides and bowls are male or female 10mm, 14mm or 18mm glass on glass joints. These are glass fittings designed to attach modular pieces together, a 14mm male joint fits securely into a 14mm female. A heady bowl or slide is a great way to add some art to a scientific waterpipe. This is just a small sample of the selection of available products. For the most up-to-date inventory, pricing and selection please call or visit the store.