Features: 1. The chain can bend unidirectionally. It stretches out while open window and retract to opener inside after closing window.  2. Double layer chain, more durable and not easy to break off.  3. Equipped with overload protector and can open and close for 20000 times.  4. Smart design with strong function.  5. Locking force reach 2000N. Push/Pull force 400/600N.  6. Working temperature: 20℃~75℃.  7. Suit for multiple window types.  8. For bulk purchase, shell with different color is available.  9. Working speed: 9mm/s.     Note: The remote control is included battery.  Motor doesn't support set open limit by itself.  DC24V motor is prohibited to connect 220V power directly, it must be used with a AC100-240v TO 24v switch.  Kit 1: Gray Chain length 300mm, body 420mm, can be used with 220 TO 24V power controler or transformer or convertor.  Kit 2: Gray Chain length 300mm, body 420mm + AC100-240V to 24V Normal switch support connect to wind/rain sensor.  Kit 3: Gray Chain length 300mm, body 420mm + AC100-240V to 24V Normal switch + 433mHZ remote, support connect to wind/rain sensor.  We also provide smart switch that support control actutor by Tuya phone APP or 433Mhz remote, also have switch which support setting stroke length of motor.  Package included:(optional) 1 x Body 420mm only(Kit 1).  1 x Body 420mm +Normal switch (Kit 2).  1 x Body 420mm +Normal switch+Remote control(Kit 3)