TechPowerUp published a review on the VGN Dragonfly F1 Pro Max
A quote from the article:
VGN is a domestic Chinese brand, and has a highly appealing budget option in store: Coming with PixArt's PAW3395 sensor, Kailh GM 8.0 main button switches, and up to 130 hours of battery life, the 55 g Dragonfly F1 Pro Max is also compatible with true 4000 Hz wireless polling.VGN Dragonfly F1 Pro Max Review