Pocket Chainsaw — 'World's fastest cutting pocket saw'

From the website:

Pocket Chainsaw® — Military–Survival Compact Saw

World's fastest cutting pocket saw

This portable tool used by the military comes in its own 3" carrying tin and is a must-have for any backpacker or outdoor adventurer.

Whether you need wood for a fire or to clear away heavy brush or a trail, this survival cutting saw does the trick.

Wrap the saw's 124 bi-directional teeth around the object you need to cut down — the teeth work on both the downstroke and upstroke, which means you can drop a 3" tree in 10 seconds.

Ideal for survival, hunting, camping, and hiking — don’t think of going on your next trip without it.

Many uses: Trim branches, brush, roots, cut firewood, lumber or clear trails and more.

This portable hand chain saw wraps around wood to cut on three sides simultaneously.

Perfect for survival safety.

Keep one in the auto.

SPECS:

• 28" long

• Coated for corrosion resistance

• High strength heat-treated steel

• 124 bi-directional sharpened teeth

• Can be used by one or two persons

• Packed in compact carry-tin — 3" x 7/8"

• Military-Survival Model has ring handle-brackets for cut-your-own wood handles

$19.99 here.