Closest would be the Hella Twin Trumpet airhorn and Stebel GP3 3-trumpet airhorn (just disregard the 3rd longest trumpet) at 795Hz and 840Hz. They are way louder than electric trumpet horns especially if mounted upfront and the trumpets angled slightly towards the front with no obstruction, maintained with compressor oil, used with atleast a 30-amp relay with a 30-amp fuse, and gauge-12 wires. I'm using a Stebel GP2 with the shorter trumpet (795Hz) angled slightly towards the front and the longer trumpet (630Hz) pointing towards the ground and maintained with Gun Tec liquimoly oil. Forward and peripheral coverage is very good, gets you heard when you need to be heard, and gets the "message" through unruly drivers. The expression on their faces is priceless.
