| CPC E21B 10/54 (2013.01) | 6 Claims |

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1. A twin bit, comprising:
a main bit; and
an auxiliary bit, wherein
a first carbide tip having a mountain shape protruding in an excavation direction is arranged at least on a top portion and a bottom portion that are located on a front end of a first base portion of the main bit,
a second carbide tip having a mountain shape protruding in the excavation direction is arranged at least on a top portion and a bottom portion that are located on a front end of a second base portion of the auxiliary bit,
the main bit further has a first plane portion and a second plane portion located on an opposite side of the first plane portion in an orthogonal direction to the excavation direction,
the auxiliary bit further has a third plane portion in the orthogonal direction,
in the orthogonal direction, the third plane portion, the second plane portion, and the first plane portion are arranged in order such that the second plane portion is disposed between the third plane portion and the first plane portion,
the second plane portion is arranged between the first carbide tip and the second carbide tip, and
an apex portion of the mountain shape of the second carbide tip of the auxiliary bit is located further behind an apex portion of the mountain shape of the first carbide tip of the main bit in the excavation direction.
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