Trojan UVMAX UV Quartz Sleeve: Replacement Sleeve for Trojan UVMAX 28E, PRO 7, E4 systems. Sleeves must be wiped clean frequently. Replace sleeve if fouled or damaged.Specs Finish kind: Domed ID: 0.71″ or 18mm ± .2mm OD: 0.81″ or 20.5mm ± .2mm Duration: 24.88″ or 632mm ± 3.5mm Genuine Viqua quartz sleeve for the Trojan UVMax 28E, PRO 7, E4 systems. The UV Max 602733 Quartz sleeve supplies thermal protection for the system UV lamp and protects it from conceivable water injury.