For those of us looking to save energy, and, consequently money in challenging times this product represents a low investment which appears to yield an excellent return.
Installation is very simple - you simply cut the foil along the nearest preprinted guideline, cuff the top of the sheet, slide on the plastic slide/holder and drop into place behind your radiator. Yes, it is that simple. A couple observations; as reflected in other reviews the sizing assumptions are quite conservative e.g. a ten radiator pack fits ten very small radiators. Also, if like me you have a number of long in width but low height radiators you are likely to need a few more of the plastic slide on holders otherwise the foil will buckle in the middle. This isn't a problem as the plastic holders are very cheap and can be bought without the foil from Radflek.
Additionally, one of the many packs I have ordered was mislaid in the post - I sent an e-mail to Radflek via Amazon on a Sunday afternoon and it was answered within 15 minutes! I get the impression Radflek is a very passionate company. Their passion is justified as few things this inexpensive yield such an advantage. When I sit near the radiator in my study which is fitted with Radflek foil the room is significantly warmer, and, I believe, you can feel that more heat is reflected back from the radiator into the room. As a result of my satisfaction with this product I am fitting it to my parents house which is significantly bigger than my own and therefore should yield even more advantage.
Finally, if the pennies are tight, even if you can only afford to put Radflek on the radiators flanking the outer walls of your home it is well worth it.
In summary, very effective, and, in these times there won't be many investments that give you as good a yield as Radflek radiator foil! Recommended.