Adama Barrow, representing a coalition of opposition parties, is posing the greatest challenge to Jammeh's rule
At a press conference in the capital, Banjul, the Independent Electoral Commission (IEC) displayed three metal drums representing the three presidential candidates contesting a December 1 election in this tiny west African state.
Voters enter a private area that is curtained off where they drop a marble into one of the three drums that are painted with the party colours and emblems, and a bell rings confirming a vote has been cast.
"It's unique and we are very proud of it," said IEC vice-president Malleh Sallah, explaining how the Gambian Public Works department dreamt up the idea six decades ago.
Electoral officials say the system all but eliminates spoilt ballots and allows illiterate Gambians to vote more easily, while ensuring only one vote is cast per person.
Sawdust or sand is sprinkled on the bottom of the barrel so that no second sound is heard.
On Thursday President Yahya Jammeh is hoping to return for a fifth term in power but is facing an unprecedented surge in support for the opposition.
Adama Barrow, representing a coalition of opposition parties, is posing the greatest challenge to Jammeh's rule, while Gambian Democratic Congress (GDC) candidate Mama Kandeh is standing as the third candidate.
The country has around 880,000 eligible voters.