Product details:

Viqua (QSO-600) Replacement Quartz Sleeve for UV SystemsQuartz sleeveAll Viqua UV systems include a quartz sleeve, which surrounds the lamp. The quartz material used in Viqua's quartz sleeves are a 100% fused silica which lend to the sleeve's high transmittance. A high transmittance is important as the UV light must travel through the sleeve to get to the water. Compatible with VP600, VP600M Professional UV systems