D'Addario EJ80 Phosphor Bronze Octave Mandolin Strings (Medium, 12-46) — is well suited for an octave mandolin.
Designed specifically for octave mandolins of various scales. 
Gauge: Plain steel for the unwound strings (.012/.012) and phosphor-bronze wound for the heavier ones (.022/.022, .032/.032, .046/.046) in the Medium (12-46) version. 
Loop-end construction so it fits a variety of tailpiece/bridge setups. 
Tone described as “warm, bright, and well balanced” thanks to D’Addario’s phosphor bronze winding.