Mechanism for adjusting the resistance value of an earth electrode connected to an electrification unit of an electric fence, includes a control element for causing the resistance value of the earth electrode to vary. An engine cooling coolant is made to flow as a cooling medium of the water jacket of the exhaust manifold. If it is desired to alter a second digit of the data value of the memory cell, the memory cell is shifted to a third data state if the memory cell is in the first data state and shifted to a fourth data state if the memory cell is in the second data state. Risers may be included to provide additional support for a firearm by securing in place a barrel or a stock. A crack prevention structure is constituted of bent portions that are provided at the lead portion and bent toward the LED-mounted side, low-stress resin portions located on the side opposite from the LED-mounted side with respect to the bent portions, and end portions of the light-transmitting resin put in contact with the low-stress resin portions.