Drug delivery systems have been developed based on the formation of diketopiperazine carboxylate salts and microparticles containing the same. The abrasive particles are partially buried in the reinforcement layer. A user accesses an emitter of the user’s router and, using transmitted DTMF tones, controls the device. The vehicle comprises a power supply voltage detector for detecting a voltage of a power supply, and a control unit for controlling the electric motor of said variable gear ratio steering device in accordance with the detected voltage. This golf ball has a high commercial value because of its visual impact and high quality feel, and because it achieves a bright, color-saturated effect without the yellow cast typical of conventional golf ball surfaces.