As of December 2015, most of the Kestrel 4000 series has been DISCONTINUED and replaced by the Kestrel 5000+ series.  It has the same and some added functions along with some physical and connectivity improvements, like IOS capability.   

Details of the changes and advantages to the new 5000+ series

Here is a VIDEO showing the 4000 vs the new 5000 series

Discontinued 4000 Kestrel Meters Series