A makiwara is traditional Okinawan training tool used for developing  proper striking technique and power. It serves a similar purpose as a heavy bag, but differs in that it consists of a stationary post rather than a swinging bag.  A heavy bag swings backward when punched, which means that the highest amount of resistance is encountered on first impact before the bag starts to move.  By contrast, when a makiwara is punched it causes the board to flex such that the resistance pushing back against the fist increases the farther it bends. This provides feedback on proper technique (a bad punch will simply bounce back) and helps to develop power because it requires the transfer of force deeper into the punch than is needed to move a heavy bag.