found this in the back of the operators manual. TM 9-2320-361-10
4210-01-149-1356 Extinguisher, Fire, Dry Chemical, 10-B:C
Potassium Bicarbonate Base (Purple
K), 5 lb. Disposable, Commercial Item
Description A–A–393, Type 1, Class
2, Size 5, with mounting bracket.
Hope it helps