I don't have any experience with Stack-On, but after reading the ad it says it's not fire rated. IMO spend the same amount of money and get something about the same size at Lowe's that *is* fire-rated. It protects just that much more.
EDIT: This is not meant to be "thread crapping", just personal observation through personal experience and reading the attached advertisement. If a person likes the Stack-On brand, then by all means buy one. Like I said, I don't have any experience with this actual brand. Mods please delete if this post breaks any rules.