40 Watt Quartz Sleeve (Part#20340, new style--Post 1998). The outside diameter of this Quartz Sleeve is 1". Pre-1998 sterilizers have a different Quartz Sleeve, which we do not carry. Fits the following Emperor Aquatics UV Sterilizers:40 Watt Smart UV Sterilizer, Part#0204080 Watt Smart HO UV Sterilizer, Part #02508080 Watt Smart UV Sterilizer, Part#02080 (takes two 40 Watt Quartz Sleeves)