International connector backflow preventor

Hi, has any european/dutch any clue what kind of parrallel thread connector is best to buy to connect the pressure vacuum breaker? I bought the watts pvb https://www.watts.com/products/plumbing-flow-control-solutions/backflow-preventers/vacuum-breakers/800m4fr/800m4-fr-qc-1 but have problems finding an correct connector. Most EU connectors use bspp. These dont seem to fit on this model (differnt size). Still from the technical spec i cannot derrive if it is npt or other standard (and which size. The inlet is 1 inch and rectangle at the beginning… but i hope to find a right buy (already 2 wrong buys). Anyone got experience for the right eu connector?

some background info.