There is an observation window on the hatches available for watching during operation. 检修口上设有观察窗，在搅拌过程中方便观察。
The outer door is a polyurethane foamy one with a glazing unit observation window, for better perspectivity and heat preservation. 外门为聚氨脂发泡门，中空玻璃观察窗，透视性好，保温性能好。
