Glorious Model O- @ TechPowerUp
 

Describing the Glorious Model O- is rather simple: it is the Model O, just sized down. As a consequence, the weight has come down to 58 g, but everything else that made the Model O a success has remained the same: PMW3360 sensor, Omron switches rated for 20 million clicks, a flexible cable, and high quality mouse feet.

https://www.techpowerup.com/review/g...odel-o-minus//