Effective Replacement: Affordably priced replacement for the VIQUA 602733 quartz sleeve. Compatibility: Replacement Quartz sleeve for the UV lamp in the VIQUA E/E+/E4/E4+/E4-V, Pro 7, & UVMax 28 series of ultraviolet water treatment systems. Made in the USA: US Water Filter replacement quartz sleeves are manufactured in the USA to provide the highest level of performance and peace of mind. Long Service Life: Quartz sleeves can be cleaned and reused, but if your quartz sleeve, cracks, breaks, or the becomes permanently cloudy and can not be cleaned it needs to be replaced. Included Parts: Box contains USWF brand replacement quartz sleeve. The quartz sleeve is an important part of the UV water treatment system. It protects the UV lamp from coming in contact with the water while allowing the UV light to penetrate the water. Minerals from the water will build up on the sleeve over time causing the sleeve to become cloudy not allowing the UV light to penetrate the water as effectively. How quickly the minerals build up on the sleeve will vary depending on your water hardness, and if you have hardness of over 7 gpg you should install a water softener to treat the water before your UV system. Once the mineral layer on the quartz sleeve cannot be removed via cleaning, or the sleeve cracks or breaks it's time to get a replacement. The US Water Filters USWF-350045 is a replacement for VIQUA 602733 for use in the VIQUA E/E+/E4/E4+/E4-V, Pro 7, & UVMax 28 series of ultraviolet water treatment systems.