8 watt Aqua Ultraviolet sterilizer, 2 inch black unit with wiper. As a sterilizer: Maximun flow rate: 642 GPH, capacity: 5-200 gallons. As a clarifier: Maximun flow rate: 1000 GPH, capacity 5-1500 gallons which may require 50% - 70% plant coverage. For salt water applications: 70 gallons. Dimensions: 24 inch x 4 inch x 2.5 inch (LxWxH). Wiper needs 11-1/2 inch clearance