The present invention provides an insert, or sleeve, for use in a baseball or softball bat that improves power transfer from the bat to the batted ball. By using these enzymes or the microorganism, scyllo-inositol is produced. The voltage generation unit may generate first and second voltages using the power supply voltage, and may vary the relationship therebetween responsive to fluctuations in the power supply voltage. An operation ring member is rotationally operated, and a second ring member rotates in unison therewith. The heater heats the sensor barrel while in fluid communication with the fluid. This invention also relates to the treatment of skin disorders, such as hyperpigmentation and cutaneous mastocytosis, and to cosmetic uses such as skin lightening.