ProPur BIG Prepper Series + TWO 7 ProPur BIG Prepper Series + 2 - 7 ProOne SlimLine filter elements: Silver impregnated self sterlizing - Increase pH up to 9.5 - Remove glyphosate, monochloramines, pharmaceuticals and more. ProOne filters do not require priming - Ideal for just about any water source including lakes, rivers, streams, ponds, rain and tap water. Constructed of heavy duty brushed and polished stainless steel with no seams to rust or leak! Limited 2 Year Warranty - Size: 9.25 The ProPur Big can use one filter element or be expanded to 3 filters (purchase includes 2 filter elements).