A piggyback adaptor for converting your upright piano into a four-row Janko piano. This file includes one octave. For the standard piano you will need 7 of these.The purpose of the design is to offer the same fingering regardless of tonality (like a guitar) and provide freedom of thumb undertuck, thus cutting practice time by 12.No drilling! This adaptor fits on top of the pivot line of the regular keys. And can be simply removed, but if you want total stability is could be fixed to the keys with double-sided tape. If you want you can paint the black keys black.