The product ie windows are solidly made UPVC. For the past 2 years the aftercare has been absolutely abysmal. Waited 6 months last year for 1x window glass replacement and 10 trickle vent covers to be replaced. It is now another 6 Months since reporting another failed glass. Had 4 appointments for this to be replaced. First technician was ill and they rang on the day to inform me. The 2nd visit, he didn’t turn up at all. Phoned twice on the day - no joy. 3rd appointment they rang to say they didn’t have the replacement glass. 4th appointment, the technician brought the wrong size glass replacement . So we now have to go through it all again at some point in the distant future. In my opinion the 10 year guarantee is worth 5 years when you have to wait so long to get one problem sorted. When I first had the windows fitted in March 2015 the after service was excellent, but now it is horrendous. Such a shame.