https://sierramadreresearch.zendesk.com/hc/en-us/articles/4440012134043-How-do-we-figure-the-temp-rating-for-the-Puffles-when-the-customer-stacks-them-
- Puffle 55 and 40 stacked together: 15° - 20°F
- Puffle 20 and 40 stacked together: 0° - 10°F
- Puffle 40 and 40 stacked together: 15° - 20°F