DELUX M800 Ultra @ TechPowerUp
 

Compared to previous versions of the M800, the M800 Ultra is significantly lighter at 52 g. The M800 Ultra comes with PixArt's PAW3395 sensor, Huano main button switches, and up to 60 hours of battery life. In addition, it is capable of true 4000 Hz polling when used with its separately available 4K dongle.
https://www.techpowerup.com/review/delux-m800-ultra/