I am using the REST API (https://api.windy.com/api/point-forecast/v2) to get wind vectors at a certain latitude and longitude. How can I use "levels" to get wind vectors at 3000ft above sea level?

In the API documentation there are examples of putting "300h", "800h" in the "levels" parameter in the REST request, but I don't know what these "h" units mean.

I have seen mentions of "geopotential height". Is this similar enough to "meters above sea level" that I could use the former as a practical stand-in for the latter?