In-line, high capacity, mechanical particle filters that offer more surface area per size of the filter by using a deep pleated, reinforced, reusable, polyester cartridges. Filter housing made of corrosion-proof ABS plastic. When cartridge needs cleaning, simply unscrew locking ring on top of filter, lift out of cartridge, hose it clean and replace. All filters have air bleeder and drain plug. Three sizes available 25 sq. feet, 75 sq. feet and 100 sq. feet surface area. An optional cap (RTL540) which has an inner chamber that allows you to put chemicals such as bromine, chlorine, tablets, etc. Each come with a spring actuated by-pass allowing 100% filtration of the water on low speed pumps. For 100% filtration at all times, the bypass can be replaced with supplied plug. Optional surface mounting stand (RTL452) come with all our units. Filters some with standard 20 micron, 100% polyester deep pleat cartridges, however, a 100 micron screen filter is available.