I've never heard of one of these bits before, but I did some googling and I've copy/pasted a couple of Q&A's
'Lack of basic riding skills. The rider is too heavy handed and is unaware of correct pressure and release You only need to ride with light hands when using a Pee Wee
' Q. Why should I buy a Macs Equine Pee Wee bit ?
A. Because, not only does the Pee wee bit give amazing control requiring only light hands, it is extremely comfortable for your horse
Those are just two things I found, but it seems that it ISN'T a 'bit for all occasions' but more of a 'bit for those who can ride with consistently light contact'
I don't think it would be suitable for everyone, my horse would hate it since he likes to play with his snaffle, the rigidity (sp?) would drive him nuts!
As for where to buy one, once again google came in handy and I found this: New Horse Bits - The Ultimate Bit for Controlling Horses
The order box is on the right hand side, and it looks like it ships internationally as well.
I'd love to hear what some other people more knowledgable than me think of it?