This is a replacement quartz sleeve for the Aquascape UltraKlear 2500 UV clarifier/sterilizer (the G2 model). It's the clear tube that protects the UV bulb from water. If your old sleeve is cracked, foggy, or scaled up, replacing it can restore your UV unit's effectiveness at killing algae and bacteria in your pond. Wattage is 28 watts. Simply turn off and unplug the unit, remove the old sleeve, clean the O-ring, and install this new one. Regular maintenance part for pond owners. Ensures maximum UV transmission for clearer water. Always handle carefully – quartz is fragile. A genuine Aquascape-compatible part.