Hot Sale Manual Greenhouse Side Film Roller Roll up Opener for Ventilation. Scientific Design: Replaces traditional turbines with a scientific design for effortless operation. Durable Steel Gear: Thickened refined steel gear with double anti-rust paint finish for long life. High Torque Output: Provides 30N.m output torque for efficient film rolling and ventilation. Wide Compatibility: Supports film roll lengths up to 90m with a 1:4 reduction ratio. Cost-Effective Solution: Manual operation eliminates electricity costs while ensuring reliable performance.