Kertok is mainly made of the coconut shell. The coconut shell is emptied. Then, a wooden plank (belira) is placed on top of the shell. Two wooden sticks are fixed on both sides of the shell to prevent the wooden plank from falling down when the kertok is beaten.
A wooden stick about 1 foot long with the end striped, with rubber scraps, is used to beat the wooden plank to produce a rhythmic tone. Kertok is played in groups of eight or ten for leisure or in competition. Each group is given a chance to show their performance and the winner is decided by the tone and rhythm produced and the showmanship of the group players.