# O vs DOA Zoom App

The clearest difference is iOS requirement: O at 12.1 against DOA Zoom App's 16.6. 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.

O ships an update every 3 months, DOA Zoom App every 2 months. The most recent releases landed on October 12, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | O | DOA Zoom App |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.8 (5 ratings)](https://appshunter.io/ios/app/o-ring/id485346224/reviews)** | — |
| Number of ratings | **5** | — |
| Positive reviews | 83.3% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 2 months** |
| Monetization | Free | — |
| Size | 26 MB | 24 MB |
| Requires iOS | **12.1** | 16.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 12+ | 4+ |
| Developer | [Trelleborg Sealing Solutions](https://appshunter.io/developer/396863758) | [Shailendra Kumar](https://appshunter.io/developer/1793910413) |

## What reviewers say

### O

[App page](https://appshunter.io/ios/app/o-ring/id485346224)

This app helps users calculate O-Ring dimensions and find compatible materials for their applications. It provides recommendations based on ISO standards and supports both metric and inch measurements.

**Highlights:** O-Ring housing calculation, O-Ring size recommendations by ISO standard, Quick search by national/international standards, O-Ring tolerance calculation, Metric and inch unit switching, Chemical compatibility check, Integration of Trelleborg Sealing Solutions Videos

**Features:** macOS Compatibility

**In-app purchases:** none


### DOA Zoom App

[App page](https://appshunter.io/ios/app/doa-zoom-app/id6741471948)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is O free?

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

### Is DOA Zoom App free?

DOA Zoom App is free to download, with no in-app purchases.

### Do O or DOA Zoom App have ads?

Neither O nor DOA Zoom App shows ads.

### Which is updated more often, O or DOA Zoom App?

O ships an update every 3 months, and DOA Zoom App every 2 months. Most recently, O was updated on October 12, 2026 and DOA Zoom App on October 7, 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.*