1. surface: check the external and internal surface. High temperature air quality tube surface should be very smooth, no stains, no wrinkle, no rough and uneven.

2.螺距：弹性钢丝及玻纤线螺距吻合，缠绕均匀。

2. pitch: elastic wire and glass fiber line pitch coincide, winding is uniform.

3.弯曲：产品弯曲自如，有弹性

3. bending: the product is flexible and flexible.

4.材料：好的高温风管采用优质硅橡胶制作，耐温耐腐蚀性更强。缠绕在弹性钢丝两边的玻纤线采用的是和基布一样的材料，同样具有耐温阻燃的效果，劣质的高温风管通常为节约成本采用的普通尼龙线，不耐温，不阻燃。

4. material: good high temperature wind pipe is made of high quality silicone rubber, which is more resistant to temperature and corrosion resistance. The glass fiber line wrapped on both sides of the elastic steel wire is made of the same material as the base cloth, and also has the effect of temperature and flame retardance. The inferior high temperature air pipe is usually used for saving cost, and the ordinary nylon line is not resistant to temperature and flame retardance