Q: Is it the size fit for US standard hose?
A: No, please note that the thread size is 7/8"-20 UNEF Male Thread Inlet.
Q: Why does the water pressure seem too low?
A: Firstly make sure your water supply is normal, then check if the handle can turn on and off normally.
Q: What does the O-ring used for?
A: Put the ring in the handle. It can help you hold the handle, free your hand.
Q: Can I use the spray valve for home kitchen?
A: Yes, you can. Just make the thread size is right.