AmerockBPR7566G10 Self-Closing, Partial Wrap Hinge with 1/4 Inch (6mm) Overlay - Satin Nickel Pack of 2

how do i measure i dont know if i need 1/4 or 3/8 or 1/2 inch

Is this really the price for one pair? i just ordered these and you had them for under $6 a pair!? i can buy these all day long for under $4 a pair.

It is my understanding that this is a set of two hinges. Is this correct or are these hinges being sold separately?

How do you adjust hinges city go up and down