Yield and Revenue Protection are the most common types of insurance used for commodity crops, such as wheat and barley.  These are both multi-peril crop insurance (MPCI) products, so they cover losses caused by a range of events--hail, drought, fire, excess moisture, etc. 

These two policies are just what they sound.  Yield Protection insures against yield losses, and Revenue Protection insures against revenue declines, providing protection in the event yields are normal, but prices decline. (Although, there are certainly circumstances where RP does not pay and YP does, such as when yields are low and prices are high.) 

The two types of Revenue Protection, RP and RP-HPE, differ in the way that the revenue guarantee is calculated. (The HPE stands for Harvest Price Exclusion.)  RP uses the greater of the projected and the price at harvest time, while RP-HPE uses the projected price only.  Prices are determined by the futures market.

Check out the comprehensive guides below for more specific information:Tractor

Single peril crop insurance is also very common in Montana and is offered by the Montana Department of Agriculture offers single peril hail insurance.  Rates vary by county. A list of eligible crops and county rates are available on the Department of Agriculture's website.  As the name implies, this type of insurance covers damage from hail only.