EVMs replaced the paper ballot system in the Kerala State elections in 1982 and are now used during Lok Sabha and Assembly elections. EVMs are easy to operate, reliable, eliminate the possibility of invalid votes, make the process of counting faster, and are easier to transport compared to ballot boxes. Only two Indian public sector units manufacture EVMs: Bharat Electronic Limited and the Electronics Corporation of Indian Ltd. EVMs contain a control unit, which is with the polling officer, and a balloting unit, which the voter enters in order to cast her vote. Names and symbols of parties are shown on the machine and the voter presses the button next to the party of her choice.