Long dremel bits, where to buy?

I'd also recommend something with more "beef" than a Dremel, I broke my old one when it chattered trying to clearance the pushrod holes in some aluminum heads. I bought a bigger one and also the flex extension so if that ever happens again it'll just toast the extension instead of the Dremel itself.

Although honestly i'll probably not use my Dremel on cylinder heads again, if I need to i'll get a proper die grinder instead.