The water flow and pressure did not decrease at all after its installation (previously I had nothing centralized). I connected it with brass fittings. The galvanized ones I had were full of sediment and rust, so now the water flow has increased a bit. Now I protect faucets, toilets, boilers, the other filter on the faucet, and everything else from pebbles and mud. It has a brass thread. The key is sold separately for about 1.90. The flange on the inside needs occasional lubrication with Fermit lubricant or another eco-friendly solution for drinking water, or with the special product from Atlas Filtri (Lubrikit). I think it also has a 1/8" port for a pressure gauge. I put a 25μm polypropylene thread replacement inside and everything is fine. Central supply filters are necessary.

For those who believe that magnets can soften water (even for a day or two), instead of spending a lot of money on installing a magnetic water softener, they can attach externally to the transparent plastic through which the water flows, for example, 4 neodymium magnets N52 (also available on eBay for 5 euros) and secure them with a thick rubber band. The magnetic field passes through the transparent plastic cover and reaches the water.

For a detailed analysis of filters, consult a good plumber below, although it makes the system more complex with bypasses, etc.
https://www.youtube.com/watch?v=SV_q4tvol2I