This test jar is 12" tall and made from high-quality glass. It can accommodate a hydrometer for taking gravity and Brix readings for beer, wine, cider, mead...you name it! The plastic base stabilizes the test jar for easy use. Simply use a siphon to acquire a sample, fill the jar about 2/3rds full, place your hydrometer in the liquid and give it a spin! Some people prefer the inert qualities of glass. This is the right test jar for them!