The Black ones are @ 1.30 mm, the red ones are a bit thinner. The pointy tip and the small surface:string ratio allow you to get in and out of the strings quicker. Great for speed and pinch harmonics, but for me anyway, the best thing about em' is the smaller size puts my hand in a much more comfortable position for Hybrid picking. Plus, the raised letters give a good gripping surface.
Ever try the Dunlop "Stubbies"? The ones I used to use was 3mm thick and looked like a purple cough drop!!! Sure was great for speed picking though...
Ian