# USM lock C vs Zeliox ZCM6

The clearest difference is iOS requirement: Zeliox ZCM6 at 13.0 against USM lock C's 15.6. On price, update cadence, ads and in-app purchases there is nothing between them.

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

Both ship on a similar rhythm, roughly every 3 months. The most recent releases landed on October 7, 2026 and September 28, 2026 respectively.

## The numbers

| Metric | USM lock C | Zeliox ZCM6 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | Every 3 months |
| Size | 47 MB | 24 MB |
| Requires iOS | 15.6 | **13.0** |
| Devices | iPhone, iPod | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [USM U. Schaerer Soehne AG](https://appshunter.io/developer/395765701) | [Zeliox](https://appshunter.io/developer/1478320738) |

## What reviewers say

### USM lock C

[App page](https://appshunter.io/ios/app/usm-lock-c/id6467190717)

**Features:** macOS Compatibility

**In-app purchases:** none


### Zeliox ZCM6

[App page](https://appshunter.io/ios/app/zeliox-zcm6/id6740893714)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is USM lock C free?

USM lock C is free to download, with no in-app purchases.

### Is Zeliox ZCM6 free?

Zeliox ZCM6 is free to download, with no in-app purchases.

### Do USM lock C or Zeliox ZCM6 have ads?

Neither USM lock C nor Zeliox ZCM6 shows ads.

### Which is updated more often, USM lock C or Zeliox ZCM6?

USM lock C ships an update every 3 months, and Zeliox ZCM6 every 3 months. Most recently, USM lock C was updated on October 7, 2026 and Zeliox ZCM6 on September 28, 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.*