These aren't hard to fit, though you have to be careful with the double sided tape when you're sliding them behind the radiator in case it sticks in the wrong place. There are plenty of options for cutting them to size, and all you need to cut them is a pair of scissors. Once in they have an instant effect. The rooms in which I installed them are appreciably warmer, and since the whole system dissipates less heat the other radiators in the house are warmer too. I don't know if they save money or how long it takes for them to pay for themselves, but if you have a house that feels cold even when the heating is on the first thing I'd do is fit some of these.