Way better than safety pins - no holes in expensive tech shirts!
I just used the BibBits for the first time to run a 5k.  I was quite happy with them, they stayed in place through the whole run.  My only complaint was that it was hard to get the number on straight without the shirt bunching up and due to the strength of the magnets you couldn't adjust without removing the magnet entirely.  I'm thinking that it might be easier to place the number before you put the shirt on, which I will try next time.  Otherwise I'm happy with the purchase, the price was fair, shipping was free and I got them fairly quick.
Rating: 4 stars