The U.S. Forest Service wants to upgrade its current fire shelter — the same shelter that the 19 Yarnell Hill firefighters deployed —  but the effort is facing setbacks.

Over the years, hundreds of firefighters have deployed the current fire shelter and survived.

Still, their performance is limited, and, after what happened nearly four years ago, the U.S. Forest Service wants to upgrade the current shelter.

The thing is, it’s not that simple. A lot of factors must be considered. 

"Meaning they are relatively light weight, relatively durable, not toxic and not a whole lot of bulk. Current shelter is about 4.5 pounds and size of a shoe box," said Tony Petrilli, the fire shelter project leader with the forest service.

He says hundreds of materials and combinations of those materials have been tested. Weight is a big factor. Firefighters carry anywhere between 40 and 50 pounds of gear.