Satisfies class IV requirement, they are the finest horns made anywhere, sturdy cast bronze with choice of three stunningly beautiful finishes: white powder coat, polished plate brass or polished chrome bronze. Unsurpassed quality with a rich, distinctive tone. The monotone model s-o and the dual chimetone d-o air whistles meet requirements at only 50 psi air pressure and operate with an extremely small compressor-tank unit. 3-1/2" Flange base diameter.
This model: dual whistle chrome plate finish.