TechPowerUp posted a review on the Darmoshark M3 4K
A quote from the article:
As the name already suggests, the main novelty of the ambidextrous M3 4K is true 4000 Hz wireless polling. Due to featuring a larger battery, the M3 4K weighs a bit more at 66 g compared to the regular M3, and still comes with PixArt's PAW3395 sensor and Kailh GM 8.0 main button switches.Darmoshark M3 4K Review