There is no publicly available information specific to Tah Koopi, an Iranian conglomerate, so it is difficult to provide a direct answer. However, for exterior applications in very rainy climates, it is important to consider the material properties, quality, and intended use of the product. Some factors to consider include:

1. Material: The material used in the product should be capable of withstanding moisture and rain. Weather-resistant materials like aluminum or stainless steel are commonly used in exterior applications.

2. Coating or finish: If the product has a coating or finish, it should be designed to prevent rust, corrosion, or degradation caused by exposure to moisture.

3. Design and construction: The products design and construction should account for waterproofing and drainage, ensuring that water does not accumulate or seep into vulnerable areas.

4. Maintenance: Regular maintenance and cleaning may be required to prevent deterioration and ensure the products longevity in a rainy climate.

It is important to check the manufacturers specifications and recommendations for the specific product you are considering. Consulting with professionals or conducting research on the quality and track record of the company or brand can also provide valuable insights.