1x 20"x4.5" BIG BLUE WHOLE HOUSE OR TANK WATER FILTER HOUSING. THIS HOUSING IS NOT WATERMARK CERTIFIED SO IS FOR USE WHEN WATERMARK IS NOT REQUIRED. We have these housings with Watermark certification listed as item 133721877673. Only available in 1"BSP ports [diameter measures 30mm]. All big blue housings have pressure release valve. PLEASE NOTE: This is a housing only. Does not include any filters or spanner. Accommodates all standard 20"x4.5" standard water filter cartridges. Manufactured according to NSF and Water Manufacturers Association Standards. This water filter housing carries a full 12 month warranty on all parts supplied in the original order subject to our standard terms and conditions. According to regulatory standards any water filter system under constant water pressure [regardless of the brand or supplier] is required to be fitted with an AS3497 approved pressure reducing valve and back-flow prevention device. NB: Where applicable [i.e. drinking water filter systems installed in your home which are permanently connected to mains water supply and under constant hydrostatic water pressure] we supply these systems with Watermark certification. Not all water filter systems i.e. aquarium, portable, caravan, car wash, commercial, rural / agricultural and industrial water filters don't require Watermark certification. It's up to you to contact us and inquire whether the unit you intend buying is fit for your intended purpose and whether you need a system with Watermark certification, or nor. In Australia plumbers may refuse to install your water filter system if it requires Watermark certification and does not have it. Due to the higher costs associated with Watermarked products we cannot simply supply all items with Watermark as it's not required in many instances and the additional costs added to all our items would price us out of the market on the items where it’s not required. We have 50+ years combined experience in the water filtration industry and started trading in Queensland in 1992. Generally, unless specifically listed otherwise our products have a 30-day no questions asked, money back guarantee. Simply return the product to us in original condition and in any original packaging to receive a refund or replacement. If you are testing a filter to see if it fits please leave it in the original wrapping until you are sure that it fits. Note that depending on the condition of the item upon return a reworking / restocking fee may apply for any necessary repairs or replacements that may be required to bring the item back to a saleable condition. Note also that a restocking fee may be applicable for units of high complexity or where we incur a shipping fee of more than $15 to send the item to you if you are returning the item due to no error / fault on our part. Unless stated otherwise in a listing or unless you have bought an extended warranty our standard warranty on all systems and parts [not filters which are considered consumables covered under our no questions asked 30-day refund guarantee] is 12 months and covers the item for any workmanship defects if you follow the operating instructions, change all filters and consumables as recommended and the item has not been damaged due to neglect or similar reasons. According to Australian Standards the maximum recommend life of any water filter and reverse osmosis system regardless of the supplier, the installation or the system is 10 years.