Andoer Decdeal Solar Heat Sensitive Vent Opener, Automatic Window Opener for Greenhouse

Compared with single spring vent, double one has stronger thrust , more solid, and much durable. double spring vent opener can be closed manually. Elongated aluminum cylinder with paint spraying, weather resistant. Solar heat sensitive vent opener, automatic stretch or shrink vent while temperature is changing. Stainless steel accessories would last long time use.