scientific experiment invention hand power generation wind vane diy handmade material package technology small production science and education frontier

Small business operation, low profit margin, if the sold products have damage, please take photos and contact customer service for after-sales processing. Due to the large number of styles, there may be individual styles out of stock. If there is a stock shortage and we cannot contact the customer, we will send the available stock first, and if there is a stock shortage, we will contact the customer service for a refund. This store does not support any reason for quality problems, sales, etc. to return the goods. Please note that the 7-day reason only applies to individual self-used customers, and wholesale customers do not enjoy the 7-day reason. Thank you for your cooperation. The price of the small store does not include the opening of the bill. If you need to open the bill or custom, please contact the manager's WeChat.