All true about microlaryngoscopy tube (MLT) except:-

These tubes come in three sizes, 4.0, 5.0 and 6.0mm. The size 5.0mm tube is the most commonly used. Microlaryngoscopy tube (MLT) vs. standard ETT The MLT is often used in place of a standard small diameter ETT to facilitate Direct Laryngoscopic procedures utilizing Microlaryngoscopy techniques. The surgeon prefers a small diameter ETT to facilitate the view of the airway.