I bought a range of colours because I wanted to do a flowing rainbow of butterflies. They're thin plastic (a bit like plastic acetate tracing paper) and the bodies have little magnets on them, so you can use them on radiators, fridges etc.
I assumed they were from the UK because of the name of the seller but they were actually sent from Hong Kong, so don't expect to get them for a few weeks.
The butterflies come with handy double sided sticky foam pads; but I used some small square ones from my craft supplies because they didn't need cutting to size. I just stuck it over the magnet.
I did one butterfly as a test to see if it would support the weight when stuck up and it was fine. They also peeled off my wall if I put one up and needed to remove it. It did leave behind a layer of double table but I could scrape it off with a nail.
Note my walls are plain and painted, no wallpaper, so I have no idea how this would work on other surfaces - you could do a small test somewhere that nobody sees if you are worried.
I didn't get too hung up about where each butterfly went, I just trusted that they would go where they were needed and I had fun with it. I hate craft projects that become a big stress of perfectionism. It has to be fun and easy or I'll never finish.
I am so pleased with the results, its taken a really plain wall and added lots of colour and movement. Plus it was so easy - my kind of craft project!
A quick recap...