# O vs KL500A

The clearest difference is update cadence: KL500A at every 4 weeks against O's every 11 months. KL500A also leads on device support (3 vs 1) and iOS requirement (11.0 vs 16.0). On price, 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 11 months, KL500A every 4 weeks. The most recent releases landed on October 12, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | O | KL500A |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/o-ring-master/id1072051820/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 11 months | **Every 4 weeks** |
| Monetization | Free | — |
| Size | 47 MB | 31 MB |
| Requires iOS | 16.0 | **11.0** |
| Devices | iPhone | **iPhone, iPad, iPod** |
| Age rating | 4+ | 17+ |
| Developer | [GE MAO RUBBER INDUSTRIAL CO., LTD.](https://appshunter.io/developer/1078558543) | [磊磊 周](https://appshunter.io/developer/1708841052) |

## What reviewers say

### O

[App page](https://appshunter.io/ios/app/o-ring-master/id1072051820)

This app provides a comprehensive offline tool for selecting standard rubber seal sizes, including O-Rings, X-Rings, and Back-Up Rings. It offers dimension searches, housing calculations for various sealing applications, and supports multiple international standards in both metric and imperial units.

**Highlights:** Offline standard rubber seal size selection, Search for O-Ring, X-Ring, and Back-Up Ring sizes, O-Ring housing calculations for sealing applications, Supports multiple international standards (AS568, METRIC, JIS, etc.), Metric and Imperial unit support, Substitutable O-Ring size suggestions

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

**In-app purchases:** none


### KL500A

[App page](https://appshunter.io/ios/app/kl500a/id6470735168)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is O free?

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

### Is KL500A free?

KL500A is free to download, with no in-app purchases.

### Do O or KL500A have ads?

Neither O nor KL500A shows ads.

### Which is updated more often, O or KL500A?

O ships an update every 11 months, and KL500A every 4 weeks. Most recently, O was updated on October 12, 2026 and KL500A 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.*