I have 2,3 and4 horn, drill horns for sale. Mostly Dewalt, some Milwaukee and 1 Ryobi. They run off of your rechargeable drill battery. These are sold online brand new as 200+ dollars from other vendors. Mine are from second hand drills that run great. Mine are $75-$150 according to the voltages. These are great for parties, sporting events, boating or just about anything that needs some noise. These are LOUD! Will definitely get someone's attention.