Grav Labs 7" Helix Bubbler Kit - Clear The kit's three attachments pair with the mouthpiece: a spoon head designed for use with plant matter, a hammer bubbler head designed to offer water filtration, and a vapor nozzle designed for use with plant extract. The connection between an attachment and the mouthpiece is secured by a 14mm plastic joint clamp. The kit includes everything necessary to build all three assemblies, and the bubbler attachment functions best with approximately 0.5" of water