TechPowerUp posted a review on the Zaopin Z2
Zaopin Z2 Review
Weighing 66 g, the right-handed ergonomic Z2 comes with PixArt's PAW3395 sensor and 4000 Hz wireless polling. Since the main button switches are hot-swappable, the default TTC Gold switches may be swapped. Aside from 2.4 GHz wireless, Bluetooth connectivity is also on board.