If your filter is shaped like a "salami" with tubes coming in one end and out of the other - then it's what we in the business call an in-line water filter.
John Guest 3/8 in. x 3/8 in. x 1/4 in. Polypropylene Push-to-Connect Angle Stop Adapter Valve (10-Pack) ASVPP1LF - The Home Depot
John Guest 1/4 in. Push-to-Connect Stem Adapter Fitting (10-Pack) PP050822W - The Home Depot
BWT Water Filter Kit - Screwfix
Osmio Premium Caravan Inline Water Filter 12mm Push Fittings
Drinks Dispense & Water Treatment Push-fit Fittings
Replacement Inline Water Filter with Push Fit Connectors — UK Water Filters
Universal Inline Fridge Filter External Water Filter Cartridge
Whole House Water Filter System - SpringWell Water
Eco Inline Water Filter with 1/4 Inch Push Fittings
