Back rest extensions for wheelchairs are a great way to accessories and allow further support for your head. Its a very unique design that allows the user to further extend support adding comfort to your daily needs. Please note that this accessory is only useable to certain S-ERGO models and may not be applicable to all models.It is very easy to put on and take off. The tools needed are included in and can be easily done by anyone. If you wish to use this for any other models other than the recommended models, please consult your dealer for installation or other modifications in which can be adaptable to your particular wheelchair.