# O vs SCR MAXFLO™

The clearest difference is rating: O at 5.0 against SCR MAXFLO™'s 4.6. SCR MAXFLO™'s advantage is ratings volume (5 vs 1). 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 holds the better App Store score, 5.0 against 4.6. That said, the two scores are not equally well evidenced: SCR MAXFLO™ has 5 ratings behind it against 1, so its average is the more settled of the two.

Both ship on a similar rhythm, roughly every 11 months. The most recent releases landed on September 22, 2026 and September 9, 2026 respectively.

## The numbers

| Metric | O | SCR MAXFLO™ |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/o-ring-master/id1072051820/reviews)** | [4.6 (5 ratings)](https://appshunter.io/ios/app/scr-maxflo/id1077499630/reviews) |
| Number of ratings | 1 | **5** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 11 months | Every 11 months |
| Monetization | Free | Free |
| Size | 47 MB | 7 MB |
| Requires iOS | **16.0** | 16.6 |
| Devices | iPhone | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [GE MAO RUBBER INDUSTRIAL CO., LTD.](https://appshunter.io/developer/1078558543) | [Southwire Company](https://appshunter.io/developer/440338423) |

## 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


### SCR MAXFLO™

[App page](https://appshunter.io/ios/app/scr-maxflo/id1077499630)

This app calculates pressure drop, fluid velocity, Reynold's number, and friction factor for liquids and gases. It allows users to create custom projects, manage pipes, fluids, and fittings, and supports both metric and imperial units for efficient on-site work.

**Highlights:** Pressure drop calculation, Fluid velocity calculation, Reynold's number calculation, Friction factor calculation, Custom project creation, Pipe, fluid, and fitting management, Metric and imperial unit support

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is O free?

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

### Is SCR MAXFLO™ free?

SCR MAXFLO™ is free to download, with no in-app purchases.

### Which has better reviews, O or SCR MAXFLO™?

O is rated higher. O averages 5.0 out of 5 from 1 ratings, while SCR MAXFLO™ averages 4.6 from 5 ratings.

### Do O or SCR MAXFLO™ have ads?

Neither O nor SCR MAXFLO™ shows ads.

### Which is updated more often, O or SCR MAXFLO™?

O ships an update every 11 months, and SCR MAXFLO™ every 11 months. Most recently, O was updated on September 22, 2026 and SCR MAXFLO™ on September 9, 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.*