REI has these right now. I have used them for several years and had to learn not to twist the grip as you could break them. They have improved and noone I hunt with has broken one in several years. They come with a sheath and coarse and fine blades. I just carry the saw and the fine blade hunting [about 4 oz]. It is easy to find replacement blades as well though I have only dulled up one blade on a rock.

Gerber Exchange-A-Blade Saw - discounted price$14.73 original price $22.00*

I have also used other saws including Corona and Coghlan's - I use others now.
- Gerber [The slider [wouldn't stay open], the Gerber Gator Exchange a Blade [weighs twice what the cheaper one does and I can't find replacement blades] and the Myth {two teeth sizes on the same saw-no replacement blades].
- Bahco Laplander - easily the toughest and longest lasting folder I have ever used. I carry it when not hunting. If they made a bone blade for it I wouldn't fool with any others.
- Silky - I went with the 180 in fine and coarse. It cuts wood extremely well but teeth are fragile. I still want to try the fine blade on bone.