# SISTER 進發 vs Helix Angle Calculator

The clearest difference is update cadence: Helix Angle Calculator at weekly against SISTER 進發's every 5 weeks. SISTER 進發's advantage is iOS requirement (13.0 vs 16.6). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

SISTER 進發 ships an update every 5 weeks, Helix Angle Calculator weekly. The most recent releases landed on November 2, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | SISTER 進發 | Helix Angle Calculator |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 5 weeks | **Weekly** |
| Size | 18 MB | 8 MB |
| Requires iOS | **13.0** | 16.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [GT MARKET CONSULTING CO., LTD.](https://appshunter.io/developer/927846054) | [SmiCut AB](https://appshunter.io/developer/1813477031) |

## What reviewers say

### SISTER 進發

[App page](https://appshunter.io/ios/app/sister/id1198930609)

**Features:** macOS Compatibility

**In-app purchases:** none


### Helix Angle Calculator

[App page](https://appshunter.io/ios/app/helix-angle-calculator/id6745720275)

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

**In-app purchases:** none


## Frequently asked questions

### Is SISTER 進發 free?

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

### Is Helix Angle Calculator free?

Helix Angle Calculator is free to download, with no in-app purchases.

### Do SISTER 進發 or Helix Angle Calculator have ads?

Neither SISTER 進發 nor Helix Angle Calculator shows ads.

### Which is updated more often, SISTER 進發 or Helix Angle Calculator?

SISTER 進發 ships an update every 5 weeks, and Helix Angle Calculator weekly. Most recently, SISTER 進發 was updated on November 2, 2026 and Helix Angle Calculator on October 28, 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.*