@@joelcordeiro2079 those are PEX Crimp Rings. You have to have a crimping tool for them. I haven't priced em in a while, but I think you can find em on Amazon for like $20 to $40.
They are pex rings.You can also use pex crimp rings but you’ll have a small ear where the pinch was made.Use either the ring or pinch tool to clamp it on.