This update seems to deal with improvements to Elevation. I find this interesting as to be entirely honest I consider the altimeter so inaccurate that I totally ignore it. As usual, these instructions are specific to a Garmin Forerunner 910XT, and I am using a Windows laptop with Chrome.

	This little “Post-It”-style notice appears top-right on you Garmin Connect Dashboard You can see your current version, and the available update version Click on “Get Started”
	You are presented with a list of devices for which there are updates Select the “Forerunner 910XT” link
	Accept the doom-and-gloom Terms and Conditions by clicking » I agree to the above terms and want to proceed to the download page
	There are links to check and to update your Garmin Communicator Plugin (should be Version: 4.0.3.0) and your Garmin ANT Agent (should be 2.3.3).
	The Garmin Communicator plugin will download CommunicatorPlugin_404.exe which you can double-click to install.
	You are updated to Version: 4.0.4.0. Now return to the firmware update screen
	Now click on Update Software The instructions specify that your unit should be connected before you commence with the update. As the next step clearly shows that the software is first downloaded to the ANT Agent on your computer, I am sure this actually is not necessary
	Once you have clicked Update Software, you will see this progress bar
	On completion of the download you will see this message
	Now you can switch over to the ANT Agent
	This is what the unit looks like during data transfer

Changes made from version 2.60 to 2.70

• Elevation improvements:
  • Improve total ascent/descent values.
  • Improvements to reduce elevation drift during an activity.
  • Improvements to reduce spurious changes in elevation.
  • Improve elevation auto-calibration at power up and between activities.
  • Improve elevation performance when GPS is turned off.
  • Improve elevation performance after swimming.
• Foreign language corrections.
• Changes to support manufacturing.