Trojan UVMAX C/D UV Quartz Sleeve: Replacement Sleeve for Trojan UVMAX 47F, PRO 15, and F4 systems. Sleeves will have to 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: 39.09″ or 993mm ± 3.5mm Genuine Viqua quartz sleeve for a Trojan UVMax47F, PRO 15 and the F4 model systems. The UV Max 602734 Quartz sleeve supplies thermal protection for the system UV lamp and protects it from imaginable water injury.