Our window hinges are sold in pairs due to there being two hinges per window.
There are two stack heights, 13mm is standard stack height, 17mm is known as high stack. Standard stack height friction stay hinges can be made into high stack ones by adding special packers which we supply.
There have been many different makes and models of friction stay upvc window hinges but as long as the replacement pair is of the same length, track width and stack height as the originals then they will suit the window to be repaired.
It is possible (and involves no more work) to change the type of hinge fitted e.g to fit restricted hinges when the original hinges were standard. New screws are also available.