... be used in all angles. 4.Less noise when spraying. Fire Extinguisher BOV's Specifications: Name Bag on valve Other name Aerosol ... gasket, Inner gasket, Stem, Spring, Housing, Bag-on-valve connector, Aluminum foil pocket(4 layers). Material Tin, Aluminium, Nylon, PE etc ... when spraying CET ISO 9001:2000 Bag-on-valve for fire extinguisher