c. Made from special PVC material, with smooth , transparent and moderate catheter, anti-twist and easy to observe the exhaled gas.

d. An anti-X-penetration line settled, to facilitate determining  intubation position

e. soft, clean and elastic cuff,  after inflation cuff could get close to the inner wall of trachea, which could reduce risk of damaging to trachea to the largest degree during the tube moving in trachea.

f.Different side of tube distinguished by two different colored cuff.