# O vs Lumtime

The clearest difference is in-app purchases: O at none against Lumtime's 3. Lumtime's advantage is update cadence (every 4 weeks vs every 11 months) and ratings volume (17 vs 1). On price, rating, review sentiment and ads there is nothing between them.

Both are free to download. Lumtime sells 3 in-app purchases, starting at $1.99 per 7 days. O asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 5.0 for O against 4.9 for Lumtime. That said, the two scores are not equally well evidenced: Lumtime has 17 ratings behind it against 1, so its average is the more settled of the two. Written reviews split almost evenly too, at 100% and 100% positive.

O ships an update every 11 months, Lumtime every 4 weeks. The most recent releases landed on October 24, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | O | Lumtime |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/o-ring-master/id1072051820/reviews)** | [4.9 (17 ratings)](https://appshunter.io/ios/app/lumtime-free-focus-assistant/id6739972398/reviews) |
| Number of ratings | 1 | **17** |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 11 months | **Every 4 weeks** |
| Monetization | **Free** | Freemium |
| Size | 47 MB | 329 MB |
| Requires iOS | 16.0 | **13** |
| Devices | iPhone | **iPhone, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [GE MAO RUBBER INDUSTRIAL CO., LTD.](https://appshunter.io/developer/1078558543) | [红品 熊](https://appshunter.io/developer/1766515274) |

## 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


### Lumtime

[App page](https://appshunter.io/ios/app/lumtime-free-focus-assistant/id6739972398)

Create custom LED signs with scrolling text and effects for concerts, events, or everyday communication. Easily personalize fonts, colors, and backgrounds to express yourself in any situation.

**Highlights:** Customizable LED sign effects, Personalized fonts, colors, and backgrounds, Scrolling text with adjustable speed, Various text effects (bold, glow, flash), Landscape and portrait playback, Export as GIF or video, Library of scene templates

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Merlin ToolKitr Pro (Weekly) | $1.99 | per 7 days |
| Merlin ToolKit Pro (Monthly) | $4.99 | per month |
| Merlin ToolKit  Lifetime Member | $39.99 | one-time |


## Frequently asked questions

### Is O free?

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

### Is Lumtime free?

Lumtime is free to download, with in-app purchases available.

### Which has better reviews, O or Lumtime?

O is rated higher. O averages 5.0 out of 5 from 1 ratings, while Lumtime averages 4.9 from 17 ratings.

### Do O or Lumtime have ads?

Neither O nor Lumtime shows ads.

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

O ships an update every 11 months, and Lumtime every 4 weeks. Most recently, O was updated on October 24, 2026 and Lumtime on October 20, 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.*