Polar M400 vs. LG Watch Sport vs. Garmin 645 Music vs. Xiaomi Mi Band 4 vs. Amazfit T-Rex
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| PolarM400Remove Buy Now | LGWatch SportRemove Buy Now | Garmin645 MusicRemove Buy Now | XiaomiMi Band 4Remove Buy Now | AmazfitT-RexRemove Buy Now |
Basic Info | |||||
| Suggested Price | $200 | $349 | $450 | $25 | $140 |
| Release | 2014 | 2016 | 2018 | 2019 | 2019 |
Activity & Fitness | |||||
| Calories | |||||
| Cycling (Bicycling) | |||||
| Distance | |||||
| Heart | n/a | ||||
| Oxygen | |||||
| Sleep | |||||
| Steps | |||||
| Swim | |||||
Battery | |||||
| Duration | 8 hours to 30 days | 1.45 days | 7 days | 20 days | 20 days |
| Rechargeable | |||||
Compatibility | |||||
| Android | |||||
| iOS | |||||
| Windows Phone | n/a | ||||
| Mac | |||||
| Windows | |||||
Connectivity | |||||
| Bluetooth | |||||
| Cellular | |||||
| GPS | |||||
| NFC | |||||
| Wi-Fi | |||||
Display | |||||
| Color | |||||
| Resolution | n/a | 480 x 480 | 240 x 240 | 120x240 | 360 x 360 |
| Size | n/a | 1.38 inches | 1.2 inches | 0.95 inches | 1.3 inches |
| Touch | |||||
| Type | n/a | P-OLED | MIP | AMOLED | AMOLED |
Functions | |||||
| Audio Speaker | Alerts only | ||||
| Clock | |||||
| Phone | |||||
| Vibration | |||||
| Voice | |||||
Hardware | |||||
| Accelerometer | |||||
| Barometer or Altimeter | |||||
| Ultraviolet Sensor | |||||
| Water Resistance | 3 ATM | IP68 | 5 ATM | 5 ATM | 5 ATM |
Notifications | |||||
| Phone | |||||
| Emails | |||||
| Texts | |||||
Software | |||||
| Operating System | n/a | Android Wear 2 | AMAZFIT OS | Build-in | |
| Apps | |||||
| Music | |||||