I'm looking at a pair of Sparton hi-lo horns for my 65 Belvedere which is lacking any. Are those correct? What does hi-lo mean; how do they work? Is there any easy way to test them without installing them? Thanks. - Jim Jim Altemose, Long Island, NY '63 Polara 500 (Max Wedge), '65 Belvedere I (Street Wedge), '71 Bronco