Apple Watch Ultra (Trail Loop)

Apple Watch Ultra (GPS & Cellular)
Trail Loop wrist band 
 
Small Strap fits 130–160mm wrists.
Medium Strap fits 145–190mm wrists.
LargeS trap fits 165–210mm wrists.
 
49mm
100m water resistant
Swimproof and recreational diving to 40m
EN13319 certification
Depth gauge with water temperature sensor
Certified IP6X dust resistant
Tested to MIL-STD 810H
Customisable Action button
Always-On Retina display
Up to 2,000 nits
Blood Oxygen app
ECG app
High and low heart rate notifications
Irregular rhythm notification
Cardio fitness notifications
Temperature sensing
Cycle tracking with retrospective ovulation estimates
Emergency SOS
International Emergency Calling 
Fall Detection
Crash Detection
High-g accelerometer
86-decibel Siren to attract attention
Cellular connectivity
Family Setup — pair multiple watches with one iPhone