Disclosed are an amphiphilic polymer, its synthesis and uses thereof. The indicator tab has two opposing side walls connected by an end wall. The contrabass guitar includes a floating bridge and a stationary torsion block with a plurality of helically twisted tuning control rods attached. Accordingly, as compared with a structure in which a ring gear is fixedoutput power is taken out via carrier and the output gear has to be axially offset and connected to a carrier, an axial space can be omitted, to allow the power transmitting device to be downsized.