Spin Pins were on my US-wishlist for ages before I picked up them up in Miami last November . I'd didn't expect a lot from them, but have been pleasantly surprised. My hair is notoriously hard to keep up - because it's so silky, ya know? But these do the trick, and if the bun does work loose, you can get it re-fastened in a matter of seconds. They're proclaimed to do the work of 20 grips - I've never had 20 grips in my hair at once, so can't comment - but they are pretty handy to carry in your purse for an emergency up-do.
These pics don't really do the Spin Pins justice, I had just had my layered, and so there are random bits of hair sticking out - but if your hair is all pretty much one length, these are a very good option for an effortless up do. I don't mind my bun looking a little scruffy as I tend to just put my hair up when I'm at my desk at work and need my hair out of my face to get down to business.
Boots is selling them for £4.99 for two (I paid $6.99), so at least they've done the decent thing and at least tried to honour the exchange rate mechanism! While I wouldn't rave about these as I don't personally wear my hair up much, if I was that way inclined they would be a must-have piece of hairstyling kit.