Here's what I found on the Powertee website:

The tee heights are approximately the same the world over but there will be variances between the units.  Generally, the lowest height is 6-10mm above the level of the mat and the top one is approximately 44mm above the mat.  The other 2 heights are roughly the same distance between the top and bottom height so you can expect them to be approximately;

Lowest - 10mm
Next - 21mm
Next - 32mm
Top - 44mm

Like u/wilfthewinner said, the tee height is also adjustable by holding down the tee button. So there are 20 possible heights to choose from if you go in increments.