I've extracted the key information for you: `{key = 'for mac download USB Device Tree Viewer 3.8.9';}`.

It seems like you're looking to download USB Device Tree Viewer version 3.8.9 for Mac. Here are some additional details about the application:

* USB Device Tree Viewer is designed to provide fast access to information about USB host controllers and devices connected to your computer.

* It's based on the Microsoft 'USBView' sample application found in the Windows Driver Kit.

* The application offers an intuitive GUI that allows easy management of USB ports and devices.

Unfortunately, it seems like the specific version 3.8.9 for Mac is not mentioned in the provided text. However, I can suggest some alternatives:

1. You can download the latest version of USB Device Tree Viewer from the official website or other trusted sources.

2. If you're looking for a specific version, you might be able to find it by searching online or checking archives of older software versions.

Let me know if there's anything else I can help you with!

For mac download USB Device Tree Viewer 3.8.9