There are various sized friction stays (hinges), both in length and thickness.  There are also a few different types of opening, either top hung or side hung.  Side hung windows can also either have normal opening or be escape/easy clean types where the window opens right out so you can use the window to escape the house in an emergency or it can be moved for cleaning.

Window friction stays have a limited life span and will regularly fail in double glazed windows that are over a certain age, anything between 5 to 10 years old unless regularly serviced.  Faulty window friction stays may cause your window to tilt, seize or drop.  Sir Fix-a-lock can renew your stays giving your windows a new lease of life.