It's all about colours. As Winnie the Pooh said - The More, The Merrier. Functionally they don't differ from the other models, but visually they're just breathtaking. The bond with you will be established on a subconscious level and you'll be puzzled why did you pick one brush instead of another. No matter of the preferred explanation, they'll still be your trustworthy friend both at the boulder and on the rope, and with their end shaped like a screwdriver, will even provide you with an extra tool when rock climbing.
