In this study, investigators will compare the efficacy of two shapes of endotracheal tube molded by stylet in endotracheal intubation using videolaryngoscope (McGrath MAC®). The participants will randomly be divided into two groups; J-shaped tube and 60-degrees-curved tube.

Since the intubation using videolaryngoscope does not need straightened oral-pharyngeal-laryngeal axis, certain curvature of endotracheal tube is needed for the successful intubation using the videolaryngoscope.

Participants in both groups will be intubated with videolaryngoscope (McGrath MAC®). Stylet will be inserted in the endotracheal tubes and will be bent to a specific shape by the assigned group. In the J-shaped tube group, endotracheal tube will be molded to a shape similar to the blade of the videolaryngoscope (McGrath MAC®). In the 60-degrees-curved tube group, endotracheal tube will be bent 60 degrees. Time to intubation, intubation attempts and ease of intubation wil be assessed.

Inclusion Criteria:

• Patients scheduled for the surgery under general anesthesia
• Adult patients from 18 years to 65 years
• American society of Anesthesiologist physical status 1,2,3

Exclusion Criteria:

• Previously diagnosed for the difficult intubation
• Pregnancy
• Obesity (Body mass index over 40 g/m^2)