Basic Bubbler Glass Hand Pipe 32mmGrav Labs Basic Bubbler Glass Hand Pipe with Colour Accents. The team from Grav Labs release yet another fine addition to their glass pipes collection with this vibrant glass bubbler hand pipe. With a diameter of 32mm, these borosilicate made glass bubblers comes built with a built in bowl and a x cut diffuser downstem. This downstem helps create the bubbles that cools down the smoke for a more pleasant hit. Don't let the size of these bubblers fool