air valve is the direct replacement for these Horns.
(PsychoBlaster, Caboose, Bullet, Mother Trucker, Spocker, Safety, Tug, & Shart) Chrome finish;1/4 Thread to 1/2 compression fitting;12-24 Volt;California Residents: WARNING HornBlasters Generic 1/4" Electric Air Valve - VA-4C This 1/4?.