420 Science UV Screw Top Concentrate Stash Jar - Concentrate (medium) Pressed Glass - Made in Europe. Permanent, Baked on Glass Decals Holds: Tons of concentrate (50 ml) Height: 1.5 (3.8 cm). Width: 2.0 (6.4 cm) UV glass looks cool, but thats not the only reason we use it. Theres a practical purpose too. You see, the UV Concentrate 420 Jar blocks all visible light from hitting your concentrate. So what does that mean? Awesomeness. And protection from premature degrading of your meds. These new 420 Jars block all UV-B rays and the complete spectrum of visible light with the exception of violet. At the same time, they allow permeation of UV-A and infrared light. This unique combination offers optimal protection against the aging process, thus lengthening the lifespan and potency of your herb.