Which batteries does the Turbo Jet DB v3.0 take?

It fits 18–21V packs from DeWalt, Makita and Milwaukee. You need to own one of those packs, since none is included.

Does it really reach 200 MPH?

200 MPH is the peak claim. Actual airflow depends on the battery you fit, and a larger pack gives more force than a small one.

Is it a replacement for a leaf blower?

No. It is a handheld blower for small jobs like garage floors, patios and car interiors. A full-size or backpack blower moves far more volume for large yards.

What comes in the box?

The blower itself. Batteries and chargers are not included, so plan on using a compatible pack you already own.

Is it worth it over a cheap corded blower?

If you already own a DeWalt, Makita or Milwaukee battery, it saves you buying another system and works without a cord. A corded blower gives constant power but needs an outlet.