HIDGrow Grommets are used in many Hydroponics Drip Systems or as replacements for many custom hydro setups. Donut Grommet Style Sizes Available Size: ID 3/8" use Vinyl or Poly Drip Line Tubing. HIDGrow rubber grommets/seals provide an air/water tight seal. These Grommets are the same if not BETTER QUALITY! Similar to: Botanicare, Auto Pot, General Hydroponics, Eco Plus & more.