I have the single layer I think it hold 48 eggs. I wouldn't waist my money on it. The heat is the problem it spikes and drops save up your money and buy a brinsea worth every penny. Just had a 100% hatch rate.
You can not adjust the humidity and temp for the different levels. I was looking at it and quickly changed my mind Amazon has a Hovbator for the same price single tray but better quality. I would go with a Brinsea if you can get the money to buy one top quality incubator.