Fitbit Charge 4
Tech specs 
SizeDevice Dimensions: 42.7mm x 28.8mm x 12.5mm
One size (small and large bands included)
MaterialBuilt of more lightweight material including an aerospace grade aluminum case and Corning Gorilla Glass 3 display. The housing and buckle are made of anodized aluminum.
Battery lifeup to 7 days, or up to 5 hours with GPS.
Water-resistance5 ATM
Weight30 grams
Sensor3-axis accelerometer, Optical heart rate monitor, Pulse Ox, GPS, Vibration motor, NFC chip for Fitbit Pay, Altimeter, Bluetooth LE (BLE)
DisplayOLED full touchscreen, TFT
Screen size35.8mm x 22.7mm
OtherCharge 4 stores your stats and data for 7 days in between the times you sync your tracker.
Activity tracking 
Calories burnedYes
Heart rate24/7 + HRV (premium subscription)
Stress & recovery
Pulse OxYes
Respiration rateYes (premium subscription)
UV exposure
Skin temperature
Galvanic skin response
Hydration level
Calorie intake
Running features
Swimming features
Other Guided breathing, Female Health Tracking, Spotify control
Non-fitness functions 
Smartphone notificationsYes
On-board music storage
Connected payYes
Affiliate link*Amazon | Fitbit
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