Comparison

US Mobile vs CO2 on Watch & Lockscreen

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

US Mobile

Manage your mobile service with ease. Activate new lines, switch between major US networks, and track usage in real-time. Offers plans for individuals and families, with international data options and 24/7 support.

Highlights
  • Activate lines with eSIM or Starter Kit
  • Switch between major US networks
  • Manage individual and family plans
  • Add international data for travel
  • Monitor usage and balance
  • 24/7 human support
Features
Read full description

US Mobile is America’s #1 Super Carrier, offering you the flexibility to use and switch between all three major US networks anytime. Welcome to a new era in wireless. Our app is your all-in-one dashboard for activation, management, and more. Whether you need a plan for yourself or your entire family, we’ve got you covered with plans that cover every need. Plus, enjoy a FREE 30-day trial to experience it all across all of our networks! Activate Your Line: Instantly activate with eSIM on all our plans Order and activate our Starter Kit on any network Keep your current number or get a new one Add international data for travel Manage Your Line: Transfer your line to another device or network Monitor your usage and balance in real-time Top up talk, text, and data as needed Set up autopay and easily switch plans Manage Your Account: Access to 24/7 human support, 365 days a year Add other users to your account to manage lines Secure your account including two-factor authentication Refer friends and family to earn rewards Follow Us: https://twitter.com/usmobile https://www.instagram.com/usmobile https://www.usmobile.com/blog

About

CO2 on Watch & Lockscreen

Monitor CO2 levels from compatible devices directly on your Apple Watch and iPhone Lock Screen. Receive smart alerts and view real-time air quality data with color-coded visuals for quick understanding.

Highlights
  • Apple Watch complications with history graph
  • iPhone Lock Screen widgets
  • Customizable CO2 threshold alerts
  • Background monitoring
  • Live Activity for real-time data
  • Color-coded air quality visuals
Features
Read full description

Enhance your Aranet4, Airvalent or Inkbird IAM-T1 monitoring experience with an app focused on Apple Watch integration and Lock Screen widgets. (this is a companion app focusing on Apple Watch integration and Lock Screen visibility; for the original features, please use the official apps). KEY FEATURES: - Apple Watch Integration: Monitor CO₂ levels directly from your wrist with multiple complication styles (including a 3hr history graph) - Lock Screen Widgets: Keep CO₂ readings visible at all times on your iPhone - Smart Alerts: Customizable CO₂ threshold notifications - Background Monitoring: Continuous tracking even when the app isn't active - Live activity: for real-time monitoring - Color-coded Visuals: Quick understanding of air quality status DEVICE COMPATIBILITY: - Works with Aranet4, Airvalent and Inkbird IAM-T1 devices. The app is free to test and connect to your device, with in-app purchases available for premium features. This app is licensed under the standard Apple EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

US Mobile4 screens
CO2 on Watch & Lockscreen4 screens

Verdict

The call

The clearest difference is rating: US Mobile at 4.1 against CO2 on Watch & Lockscreen's 1.0. US Mobile also leads on in-app purchases (none vs 8) and ratings volume (2K vs 2). On price, update cadence, ads and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. CO2 on Watch & Lockscreen sells 8 in-app purchases, starting at $3.99 per month. US Mobile asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

US Mobile holds the better App Store score, 4.1 against 1.0. That said, the two scores are not equally well evidenced: US Mobile has 2K ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 68% of US Mobile's written reviews are positive against 50% of CO2 on Watch & Lockscreen's.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly weekly. The most recent releases landed on November 3, 2026 and October 30, 2026 respectively.

Scorecard5 real differences · 5 level
US Mobile versus CO2 on Watch & Lockscreen: the parameters behind the verdict, then further details
ParameterUS MobileCO2 on Watch & Lockscreen
PriceFreeFree
Rating4.1 (2K ratings) — better1.0 (2 ratings)
Positive reviews68.0% of reviews — better50.0% of reviews
Number of ratings2K — better2
Update frequencyWeeklyWeekly
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPadiPhone, iPad, Apple Watch — better
Requires iOS16.4 — better17.6
Further details — not scored
Size207 MB28 MB
Age rating17+4+
DeveloperUS Mobile Inc.Kevin Floch

Customer experience

US Mobile

All ratings1,944 ratings
Positive76.0%
Neutral4.0%
Negative20.1%
Written reviews590 reviews
Positive68.0%
Neutral5.8%
Negative26.3%

CO2 on Watch & Lockscreen

All ratings2 ratings
Positive0.0%
Neutral0.0%
Negative100.0%
Written reviews4 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

Bugs and requests

US Mobile

Reported bugs

5 issues
  • App freezes on login screen
  • Inability to scroll on certain screens
  • Incorrect data usage information
  • Frequent app crashes and bugs
  • eSIM compatibility issues

Requested features

5 requests
  • Improved data usage tracking
  • Easier account management options
  • Expanded international roaming support
  • Parental controls and content filtering
  • Seamless integration with Apple Watch

CO2 on Watch & Lockscreen

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

US Mobile

No in-app purchases

8 purchases

CO2 on Watch & Lockscreen

Subscriptions2
  • CO2_Monthly7 Days trial$3.991 Month
  • CO2_Annually7 Days trial$29.991 Year
One-time6
  • Small tip$4.99
  • Medium tip$9.99
  • Large tip$19.99
Show 3 more
  • CO2_Lifetime_Upgrade2$24.99
  • CO2_Lifetime$49.99
  • Extra large tip$49.99

Questions

Is US Mobile free?
US Mobile is free to download, with no in-app purchases.
Is CO2 on Watch & Lockscreen free?
CO2 on Watch & Lockscreen is free to download, with in-app purchases available.
Which has better reviews, US Mobile or CO2 on Watch & Lockscreen?
US Mobile is rated higher. US Mobile averages 4.1 out of 5 from 2K ratings, while CO2 on Watch & Lockscreen averages 1.0 from 2 ratings.
Do US Mobile or CO2 on Watch & Lockscreen have ads?
Neither US Mobile nor CO2 on Watch & Lockscreen shows ads.
Which is updated more often, US Mobile or CO2 on Watch & Lockscreen?
US Mobile ships an update weekly, and CO2 on Watch & Lockscreen weekly. Most recently, US Mobile was updated on November 3, 2026 and CO2 on Watch & Lockscreen on October 30, 2026.

Other comparisons