Group 1 - The K90 Pro Max features a dual-layer protection for its rear speakers, including a metal dust cover and a dust net, and has passed the IP68 dust and water resistance test [2] - Users can utilize the built-in speaker cleaning function or visit service points for deep cleaning if dust accumulates [2] Group 2 - The K90 series supports a Super Moon feature that activates automatically when zooming in on the moon beyond 20x [3] - The camera watermark functionality has been significantly upgraded, offering various types of watermarks and enhanced customization options [3] - Users can access the watermark settings through the camera menu for further customization [3]