This replacement sleeve will fit the H20 GrabNGo™ Water Purification System. Quartz will allow the short wavelength of UVC light pass into the water for sterilization, and keep the UVC bulb dry. These bulbs require monthly cleaning, if used with the system. Carefully remove the sleeve from the housing, and wipe clean with a vinegar solution. Be careful to NOT touch the sleeve with your bare hands. Leaving fingerprints on the glass will restrict the UVC light from penetrating the water around it.