http://www.delmhorst.com/products_hay.html

I've got the F/6 works great. I don't need any averages,,  all the hay has to be under 10% in order to bale.  Dealer's won't commit to any hay 10% or over. Weekend cowboys are somehow convinced the hay will spoil if it's anything over 10% moisture....

Sensors can be had,, and mounted on the bale chamber's but I have to know the interior moisture level. Dealer's always bury the probe clear to the head then sample the moisture.  I like the portability,, I can take the tester out of the cab,, go check the next field by squeezing hay around the probe end as hard as I can. Experience has taught me there is 2-3% difference between hand squeezing and testing an actual bale and I don't have to move the baler around just to take a moisture sample.