The great thing about perfect fit and Intu solutions for UPVC window frames is that there is no need for drilling any holes. Both systems have specially formed brackets that slide between the rubber seal of the window frame and the window. These systems are designed for most modern UPVC windows and suitable for either Pleated, Roller or Venetian blinds. You then have the Perfect Fit international system which is designed for pleated roof blinds. The Perfect Fit and Perfect Fit International have a frame which then sits snug inside the window frame secured by the brackets mentioned above. The Intu system is slightly different which relays on slim side profiles which secure within the window frame with supporting brackets mentioned above and the head rail just clicks into place. Both systems have their pro's and con's depending on your requirements.