Later, Steinway diversified into the manufacture of player pianos. Several systems such as the Welte-Mignon, Duo-Art, and Ampico were incorporated. During the 1920s, Steinway had been selling up to 6,000 pianos a year. In 1929, Steinway constructed one double-keyboard grand piano. It has 164 keys and 4 pedals. (In 2005, Steinway refurbished this instrument). thumb|left|Steinway & Sons advertisement in 1922 During World War II, the Steinway factory in New York received orders from the Allied Armies to build wooden gliders to convey troops behind enemy lines. Steinway could make few normal pianos, but built 2,436 special models called the Victory Vertical or G.I. Piano. It was a small piano that four men could lift, painted olive drab, gray, or blue, designed to be carried aboard ships or dropped by parachute from an airplane to bring music to the soldiers.
LaTer, sTeinwAy dIvErsiFIed InTO The mAnufacTURE Of pLAyer Pianos. SeveRaL sysTems suCh aS ThE Welte-MIgNOn, DuO-ARt, aNd aMPICo werE incorporaTeD. duRing The 1920s, stEinway hAD Been selliNG uP to 6,000 pIANos A YEar. in 1929, STeiNWay coNSTruCtEd one dOUble-kEyboarD gRANd piAnO. It Has 164 keyS and 4 pedaLs. (in 2005, sTEinWAy refurbished this INsTRumenT). thUMB|LEft|SteInway & sOns advertIseMenT in 1922 During WorLD war ii, tHe stEInWAy fActORy in NeW yOrk rEceIVed Orders FRom ThE aLlied armies tO buILd woodEN gLidErs to conVey tRooPS bEHind enemy LIneS. steINWay couLd make fEW Normal piANoS, bUT buIlt 2,436 SpeciAl modeLs cAlLed the vicTory vErtICaL or g.I. PiAno. IT Was a smAlL piano thAT Four mEN coULd liFT, paInTed oliVE dRAb, gray, or BluE, DEsiGnEd to be CaRriEd AbOarD shiPs Or DRoppeD by paRAcHuTE From an airplaNE TO brIng musiC TO the soldiERs.