# SOSホイッスル vs 同心円ロケーター

The clearest difference is iOS requirement: SOSホイッスル at 8.0 against 同心円ロケーター's 17.0. 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.

SOSホイッスル ships an update every 5 days, 同心円ロケーター weekly. The most recent releases landed on October 7, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | SOSホイッスル | 同心円ロケーター |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 66.7% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 5 days** | Weekly |
| Monetization | Free | — |
| Size | 19 MB | 3 MB |
| Requires iOS | **8.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [ComNetSystem](https://appshunter.io/developer/697816110) | [Tom App Works](https://appshunter.io/developer/1874760041) |

## What reviewers say

### SOSホイッスル

[App page](https://appshunter.io/ios/app/sos/id1301828783)

This utility app produces a loud whistle sound and a blinking light when a button is pressed, designed to help users signal for help in emergencies. It offers customizable modes for both the whistle and light functions.

**Highlights:** Whistle sound on button press, Blinking light on button press, Adjustable whistle modes, Adjustable light modes, Emergency signaling tool

**Features:** macOS Compatibility

**In-app purchases:** none


### 同心円ロケーター

[App page](https://appshunter.io/ios/app/id6792966939)

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

**In-app purchases:** none


## Frequently asked questions

### Is SOSホイッスル free?

SOSホイッスル is free to download, with no in-app purchases.

### Is 同心円ロケーター free?

同心円ロケーター is free to download, with no in-app purchases.

### Do SOSホイッスル or 同心円ロケーター have ads?

Neither SOSホイッスル nor 同心円ロケーター shows ads.

### Which is updated more often, SOSホイッスル or 同心円ロケーター?

SOSホイッスル ships an update every 5 days, and 同心円ロケーター weekly. Most recently, SOSホイッスル was updated on October 7, 2026 and 同心円ロケーター on October 24, 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.*