A nail magazine includes a magazine base which has a base panel, and first and second flanges projecting from and extending longitudinally at two opposite longitudinal ends of the base panel. 5 where G is a spark gap and A is the distance between a first imaginary line and a second marginal line. Separate outside panels are coupled to pairs of vertical post within the spaced apart intervals, and separate inside panels are coupled to pairs of vertical post within the spaced apart intervals. The gate electrode is positioned in the second groove.