Bought a 4.8m set of aluminium clad exterior Ultra bifold doors for self build extension and fitted them last autumn. Could not be happier with both the doors and the service. A door did arrive damaged (minor dent caused in transit I suspect) and they replaced it immediately without any fuss. The doors and fittings are of a very high quality and were easy to install. I am a competent DIYer but have never fitted doors or windows. I installed these over 2 days myself - just with a little help to lift he doors and frame into place. The doors a very heavy! Instructions were good and if you need to call Vufold, you will speak to someone in the UK that actually knows the products - I was really impressed by their service over the phone. This was a big chunk of the budget for our extension but worth it - dont buy cheap UPVC bifold's - especially the larger sizes - they will almost certainly warp over the years, particularly if they are in direct sunlight. My doors get the sun all day in the summer and the worst of the Scottish wind and rain in the winter. So far they have preformed perfectly - only maintenance required is occasionally cleaning any dust out of the bottom channel to keep it clear to drain and the mechanism running smoothly.