It comes in 3 different lengths: 16 inch, 18 inch and 20 inch. You can hook it onto any of the lengths, so I would recommend getting the LONGEST length you'd wear it, so you have options!
This necklace is made with 100% US-grade gold-filled materials. This means you can shower, swim and live in this without worrying about it tarnishing as quickly as typical "boutique quality" jewelry. US-Grade Gold-Filled Jewelry is at least 5% gold BY LAW. Gold-Plated jewelry can be as low as .005% gold. Gold-Filled is the next best thing, after solid gold, and at a fraction of the price!