This is a brand new 1975 - 1991 Corvette Tachometer Tach Filter C3 C4 Comes with simple instructions. New improved design with a ground wire. Designed to meet or exceed OEM. Stops radio interference! There are no refunds on electrical items.     If there an issue with your order, please contact us prior to leaving negative feedback or opening a case. As you can see from our feedback, we are committed to excellent customer service.