This is the 185x75x60mm Lithium Polymer Charging Safety Bag from Ultimate Racing, and is intended to reduce the chance of damage or injury in case of a LiPo fire.   Due to the volatile nature of Lithium chemistry batteries, charging bags such as this Ultimate LiPo Safety Bag are required by many tracks, flight clubs, etc.   Dimensions: 185x75x60mm  
WARNING:   Never leave charging battery unattended. Always ensure the battery is on a non-flammable surface. Ensure flap is sealed while charging.