Take a look at the Gerber LST. It's a folder - blade's about 2 3/4 inches- with a synthetic handle. It's flat, fits in your pocket very nicely, and weighs very little.
You'll be surprised how comfortable the handle is, and how tough the knife is. I use it to field dress deer, and I have cut thru the ribcage and the pelvis of a deer with it, too. Didn't hurt it a bit. (someone said it was impossible with 'that little bitty folder'
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