ZH Currtain Window Opener ZM90: Smart Push & Pull, Customized Flexibility. The ZM90E-DT Smart Chain Window Opener features an electronic overload protection device, ensuring safety and stability during long-term use. With over 30,000 push-and-pull tests, it demonstrates exceptional durability and is suitable for various window types, including both traditional and modern systems. With chain lengths available in 300mm, 400mm, and 500mm, it meets diverse window size requirements, making it the perfect choice for smart home systems. The ZM90E-DT Smart Chain Window Opener Unique Advantages: Control: RF433, Zigbee, Wi-Fi, RS-485; Resistance then stop function; Sound control connection: Xiaodu, Xiaoai, tmall, Amazion Alexa, Google home; Smart home connection; Change direction function; Electronic overload cutoff protector; Endurance tests (30000 cycles) are carried out; Suitable for top / center-pivoted / hopper window.