The blade on my Buck 119 model is 6" long which I feel is about the most useful maximum length for me.

I could go with a shorter knife blade which I did with the recent purchase of 2 Mora Clippers, however the Buck will probably continue to be my most used. Not because of the length, rather it fits my hand great and after 12 years of ownership, I am very comfortable using it.
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Earth and sky, woods and fields, lakes and rivers, the mountain and the sea, are excellent schoolmasters, and teach some of us more than we can ever learn from books.

John Lubbock