Fungo bats are, simply put, a long, skinny, and lightweight baseball bat used for fielding practice. Typically, they are around 34 to 37 inches in length and between 17 and 24 ounces in weight, give or take a couple of ounces. They will also almost always feature a 2 1/4 inch barrel diameter to allow for more control during a swing. As you can tell, fungo bats are longer than a normal baseball bat and much more lightweight in comparison. Most fungo bats are going to be made up of ash wood while there are some maple and bamboo wood fungo bats, some composite wood fungo bats, and very few aluminum alloy fungo bats. Almost all of these designs will be under $100 with very few eclipsing that mark.
Maple bats in particular were once known (circa 2008) to potentially shatter in a way that resulted in many sharp edges, sometimes creating more dangerous projectiles when a bat broke. Maple bat manufacture evolved significantly, in cooperation with Major League Baseball, paying special attention to grain slope, and including an ink spot test to confirm safest wood grain orientation.
On June 17, 1890, Emile Kinst patented the ball-bat, or banana bat. The bat is shaped with a curve, hence the name banana bat. The creator of the bat, Kinst wrote: "The object of my invention is to provide a ball-bat which shall produce a rotary or spinning motion of the ball in its flight to a higher degree than is possible with any present known form of ball-bat, and thus to make it more difficult to catch the ball, or if caught, to hold it, and thus further to modify the conditions of the game".
Secondly, the first base fungo hits balls to the third baseman, who turns a double play with the second baseman to the normal first baseman, while the third base fungo hits balls to the shortstop, who throws to a shortened deep firstbaseman (this means that the deep firstbaseman stands closer to the shortstop than normal, so that the throw across this infield is the correct distance - this does NOT mean that the deep man stands any closer to the normal first base position - this length should always be sufficient)
The fungo is used by a coach to hit balls for defense practice. It is lighter weight, so less fatiguing to hit ball after ball. The fungo sheds its weight above the hands. The severely tapered barrel to drops weight and maintains a high moment of inertia. While the bat would be at greater risk of breaking if used in a live batting exercise, it is safe to use in practice because there are much fewer mis-hits.