The Watch Series 3 is Apple's 3rd-Generation smartwatch, with the major upgrade over the Series being the optional cellular (LTE) connectivity. The display remained the same 38 mm 272x340 or 42 mm 312x390 flexible AMOLED. The CPU has been upgraded (with a 70% performance boost) and there's a new highly-efficient wireless chip. The Watch 3 now also sports a barometric altimeter.

Apple Watch 3 photo

The Watch Series 3 will start shipping by the end of September for $329 (GPS only) or $399 (GPS + Cellular)

OLED type: 

272x340 (38mm) or 312x390 (42mm) flexible AMOLED

Atomic Force Microscopy for next-gen OLED processesAtomic Force Microscopy for next-gen OLED processes