Amazon offers the Hella Supertone 12-volt Twin Horn Kit
, model no. 003399803, for $40.28. Clip the coupon on the product page and the price drops to $32.22
in-cart. Plus, Prime members bag free shipping
. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $7.09.) That's the lowest total price we could find by $26. The kit includes one high-tone horn, low-tone horn, 12-volt relay, and two mounting brackets. Each horn measures 8.58" x 7.32" x 3.5".