Double glazed doors which need a 48mm pz handle are generally quite old and the handles are being phased out.
You may find that the screw centres on your existing handle are different to the ones on this page however these are the only handles available now.
If you have a good level of DIY then it is possible to redrill your door to suit the screw holes on the replacement handles however it is very important that you check the position of the lock gearbox inside the door before starting to drill. You will need to unscrew and remove the lock from the door to check this.
This is essential as drilling in the wrong position will damage your lock and could mean a new door is needed.
** Double check the position of the lock behind the handles before attempting to redrill the door **