Beyond the strength number, you should look at a few other specs on the box or in the spec sheet:

• Nicotine strength: Usually 20–50 mg/mL for salts, 3–18 mg/mL for freebase. Know what your market buys.
• PG/VG ratio: Higher PG means more throat hit; higher VG means more vapor. Your customers will have preferences.
• Volume (mL): This tells you how long a disposable lasts. It's not the same as puff count—don't rely on puff counts; they're marketing numbers.
• Nicotine type: Salt or freebase. Write it down.

These four specs tell you most of what you need to know before you even open a box.