# USB vs 水質空品檢測寶

USB and 水質空品檢測寶 are too close to call on the numbers: across 6 compared parameters — price, update cadence, ads and in-app purchases among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

USB ships an update every 3 months, 水質空品檢測寶 every 6 weeks. The most recent releases landed on October 27, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | USB | 水質空品檢測寶 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 6 weeks** |
| Size | 201 MB | 41 MB |
| Requires iOS | 13.0 | **12.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Merry-Link Co.,Ltd.](https://appshunter.io/developer/1040729128) | [Ju Cheng Shih](https://appshunter.io/developer/1110051522) |

## What reviewers say

### USB

[App page](https://appshunter.io/ios/app/usb-921/id1539400908)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### 水質空品檢測寶

[App page](https://appshunter.io/ios/app/id1574617049)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is USB free?

USB is free to download, with no in-app purchases.

### Is 水質空品檢測寶 free?

水質空品檢測寶 is free to download, with no in-app purchases.

### Do USB or 水質空品檢測寶 have ads?

Neither USB nor 水質空品檢測寶 shows ads.

### Which is updated more often, USB or 水質空品檢測寶?

USB ships an update every 3 months, and 水質空品檢測寶 every 6 weeks. Most recently, USB was updated on October 27, 2026 and 水質空品檢測寶 on October 30, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*