The A-flat clarinet is a member of the clarinet family, smaller and sounding a perfect fourth higher than the E♭ clarinet. The A♭ is rare, but even less common, obsolete instruments in C, B♭, and A♮ are listed by Shackleton. Some writers call the A♭ and these other instruments octave clarinets, sopranino clarinets, or piccolo clarinets. The boundary between the octave and soprano clarinets is not well-defined, and the rare instruments in G and F might be considered as either. Shackleton, along with many early twentieth-century composers, uses the term "piccolo clarinet" to refer to the E♭ and D clarinets as well (piccolo merely meaning "small" in Italian). This designation is less common today, with the E♭ and D instruments more usually designated soprano clarinets. The term "piccolo clari