FIG. 1 is a perspective view of a first embodiment thereof;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is side view thereof as taken from the right side of FIG. 2;
FIG. 5 is a side view thereof, as taken from the left side of FIG. 2;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is a sectional view thereof; as taken along lines 8-8 in FIG. 2;
FIG. 9 is a sectional view as taken along lines 9-9 in FIG. 2;
FIG. 10 is a perspective view of a second embodiment thereof;
FIG. 11 is a front view thereof;
FIG. 12 is a back view thereof;
FIG. 13 is side view thereof as taken from the right side of FIG. 11;
FIG. 14 is a side view thereof, as taken from the left side of FIG. 11;
FIG. 15 is a top view thereof;
FIG. 16 is a bottom view thereof;
FIG. 17 is a sectional view thereof; as taken along lines 17-17 in FIG. 11;
FIG. 18 is a sectional view as taken along lines 18-18 in FIG. 11;
FIG. 19 is a perspective view of a third embodiment thereof;
FIG. 20 is a front view thereof;
FIG. 21 is a back view thereof;
FIG. 22 is side view thereof as taken from the right side of FIG. 20;
FIG. 23 is a side view thereof, as taken from the left side of FIG. 20;
FIG. 24 is a top view thereof;
FIG. 25 is a bottom view thereof;
FIG. 26 is a sectional view thereof; as taken along lines 26-26 in FIG. 20; and,
FIG. 27 is a sectional view as taken along lines 27-27 in FIG. 20.