I have a hex crimper that will do 28-6 gauge. It's from FerrulesDirect.com. Once you get to the larger size wire, I think the selection is a lot smaller and you're limited to square crimpers. Some situations work well for a hex crimp and some don't. For circuit breakers, a square crimp is better (in my opinion). My 10-6 gauge square crimper is the Pro'sKit 300-144 Lunar Crimper, Wire Ferrules AWG 10-6, Multi. A nice feature of that crimper is that the company that makes it also sells a ton of direct fit dies for other crimping. I bought an MC4 crimper die for that tool off their website and it worked well.