Creating of free-bass Kravtsov’s system keyboardallows to decide stone corner problem of accordionist’s repertouire, to adopt the accordion with equal for left and right hands systems of keyboards.The long-expected model of the instrument with elective keyboard appears that is closed to formed skills of playing on organ-piano keyboards through the point of view of instrumentation, performing and pedagogies. Now it isn't necessary for the accordionist to play on elective button system (B-griff è C-griff), that absolutely impede the art's development of playing on the accordion. The producing of such new elective keyboards has been already begun at belorussian firm “Zonta" (early “Slava”). Supposing converter are made up by mirror principle relation to right keyboard. Why so and not on the contrary for example as the bayan is? The research of this question shows that moving-and-playing processes are rapidly got right and more correspond with man’s physiology if they have mirror opposition. Especially it’s easy to detect in conductor’s manual practice. Everybody who has ever put the conductor’s stick in hands remembers how easy and comfortable to conduct with 2 hands in opposite way. But it’s strange for true conductor’s process such comfortable for physiology “parallel” because there is a special functional-arts claim for each hand in conductor process and they shouldn’t move doubling each other. And of course it requests huge efforts for overcome the nature of moving. Stepwise placement of three rows of keys, furthest away from the bellows, will allow the full functionality of use of the left thumb. 
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