Check the listing for details. Polaris 3900 Sport Rear Housing Replacement Pool Part. Condition: New. Listed at 17.95 USD. Polaris 3900 Sport Rear Housing Replacement Pool Part Polaris 3900 Sport Rear Housing (39-005)The rear housing is a replacement part made by Polaris. It is made from the same high-grade plastic material that was used for the original factory part. Making this a genuine OEM product.This rear housing was designed to not only be a protective cover for the internal parts of the 3900 Sport but to also allow the water from the pool to flow through and out the backside of the cleaner. This ensures that no water can be trapped or weigh the cleaner down in any way during the cleaning process.This part is gray and has little round openings dispersed through the entirety of the part. It sits on the back of the cleaner, so it is easy to locate and identify.