Pleated washable 20’’ x 4.5’’ inch housing used in bigblue-twinnkit also bigblue-singlekit inline single housings cartridges are described as a ‘surface filter’ which means that once the outside  surface of the fabric is soiled it needs to be washed. Can be washed and re-used up to 3-4 times before replacement. An excellent pre-filter for removing large solids and organic matter in dam, tank and bore water. The cartridge has a large surface area to maximise its efficiency, resulting in fewer change outs and is ideal for low pressure situations Suitable for domestic, tank water, irrigation, light industrial applications.