Wolfgang Amadeus Mozart's 10th piano concerto, in the key of E flat major, was written for two pianos and is now catalogued as K. 365 (or 316a). The date of completion of this concerto is still debated among scholars, though research suggests that parts of it may have been written between 1775 and 1777. Mozart originally scored it two pianos together, two oboes, two bassoons; two horns; and strings. He later expanded the orchestration with pairs of clarinets, trumpets and timpani in E flat and B flat. The structure of the piece itself is somewhat unusual, departing from the traditional piano concerto forms to establish a dialogue between the soloists, and keeping the role of the orchestra to a minimum.