Sax’s keyed bugles show some similarities with French instruments of the period, but they also feature some special innovations. As is typical for French and Belgian instruments, for example, Sax’s keyed bugle is made of brass, not of copper as are English keyed bugles. Sax's instrument is fitted with seven keys, a ratchet tuning slide, an attachment for a lyre near the bell, and even retains its original mouthpiece.