If a product has a Roor logo you know it’s quality. For over 20 years they have been the leader in high end, high quality glass and they’re accessories are no different. These downstems are made of a high quality Schott-Duran glass, that is extremely heat and scratch resistant. These downstems get there name from the "gridded" pattern on the of each one. The tiny pattern forces all the smoke to be filtered through in small amounts for the best cooling and filtration. Each Roor Gridded Diffused Downstem comes in your choice of size for Straight neck (7.5" long) or Beakers (8.75" long) and fits 18mm bowls. These glass pieces are handmade to order, please allow 2-4 weeks for delivery. Looking for 14mm? Check out the Roor Low-Profile Gridded Downstem.