Quartz Sleeve for R-Can Sterilight S12Q / S12Q-PA / S12Q models QS-012 The R-Can / Sterilight QS-012 Quartz Sleeve is what protects the S36-RL bulb from the water flowing through the S12Q and S12Q-PA Ultraviolet models by R-Can / Sterilight. Ultraviolet light then shines through the QS-012 into the water which creates the germicidal action of the ultraviolet system. Periodically, a layer of mineral (such as calcium, magnesium and iron) may form on the surface of the QS-012 quartz sleeve, possibly impeding the radiation of ultraviolet light into the water. It is therefore necessary to clean the quartz sleeve periodically. A water-tight seal is created at each end of the QS-012 by o-rings. These should be replaced on a yearly basis when the S12Q or S12Q-PA ultraviolet bulb is changed and come supplied with the QS-012 quartz sleeve.