These are efficient
I purchased two of these for the draft horse rescue where I volunteer. They were very easy to set up. My only concern is that they also attracted beneficial honey bees as well as flies.
Works grest an its cleaner than the rest
I bought this trap as it said it was good to catch and attract biting horse flies. Since it suggested they be hung in the sunlight, I put them around the pasture on fences where they got the most sun. After about 2 days, it was catching a lot of flies and the horses were stomping a lot less. I will be buying more of this product.