1. Conventional shading in greenhouses is external shading and internal shading. The external sunshade is at the top of the greenhouse, at least 50 cm higher than the highest point of the roof. Internal shading plays the role of auxiliary shading and heat preservation in greenhouse. 2. From the driving mode, there are mainly rack-and-pinion track installation and cable transmission. At present, the popular models are Dutch cable drive and Korean cable drive. 3. Sunshade nets generally adopt products with shading rate and service life guaranteed by regular manufacturers. To compare the weight per square meter, whether it is brand-new raw materials, recommend products from Shanghai, Beijing and Changzhou; 4. Recommend the motors in Guangdong and Zhejiang, and do not explain the reasons. 5. The transmission system has been used by regular manufacturers for more than five years. It is recommended to know the products of Beijing Greenhouse Materials Company. 6. Internal and external shading is an indispensable system in the greenhouse. 7. Weld a frame with a spacing of 4 meters or 6 meters, and ask Beijing Zhonghe to buy materials to guide the installation. Square meter cost 10-30 yuan.