It is great in high stubble crops (with stripper headers, canola, hemp, corn, sunflower, etc.). It fits beneath the feeder house, to be kept safe and high enough away from the tall stubble compared to the back axle mounting point.
When attached to the header, it allows you to understand your header losses as well as your losses while using a chaff spreader/chopper implement.
It is a must-have for anyone that is harvesting grains and specialty crops.