Just looking at the chart for the incubator. I've got a 40* incubator, but find it a bit cold for the shoulder season, so I'm pondering buying a thicker quilt, but I'm a bit confused...

The 40* F model weighs 19 oz.
The 20* F model weighs 22.5 oz.

The 40* F model has 7 oz. of down.
The 20* F model has 12 oz of down.

How is this possible? If the 20*F has 5 oz more down, shouldn't it weigh 5 oz. more? Am I missing something or is it a typo?

Math was never my strong suit and I can't sew to save my life, but I'd expect the 20* model would weigh in at 24 oz.at least...