Lipo batteries are notorious for spontaneously self igniting when not cared for properly or charged too quickly after discharging. Made from a fiberglass woven fabric, this lipo sack is fire retardant and we strongly recommend charging your lipo batteries in these bags. Never leave a charging lipo unattended. These are cheap insurance against a possible flameout or fire. This bag is 25x33 cm (10"x13"), and will fit (4) Inspire batteries or (6) Phantom batteries.