Here is a PDF info-sheet, plus photos, about the very handy magnetic strip secondary glazing which I have on my windows.
I also in 2015 made a short (9-minute) video, in which I and a colleague tell you about its advantages and show you how it's installed.
As at February 2023 it's had 180,000 hits, and hundreds of useful comments; please do watch it!
Magnetic strip secondary glazing is inexpensive and easy to do; it's unobtrusive (good for conservation zones and listed buildings) and very long-lasting; it does the same job as expensive secondary glazing systems.
I achieved brief fame in 2014 in a piece in a national newspaper, talking about this very useful energy-saving measure.
Click on photo for larger image
Also useful for fly-screens: You can also make fly-screens for use on your windows when the acrylic isn't on them. A few years ago I bought self-assembly window fly-screens and added magnetic strip on the back of the frames. Have a look at how I used them.