I religiously use Shoo Fly Leggins. I love them! My entire herd wears them now.
Pros: They work like a reverse lamp shade, fastening with velcro around the pastern/coronet and getting wider as they go up the leg. There is little to no contact with the majority of the lower leg, which decreases the risk of skin funk from prolonged contact or having the boot tighten on the tendons. Because of this, I feel comfortable leaving on overnight if I have to. And believe it or not, they work-- the flies really don’t fly down the open top. The price is very fair, around $50 for a set of 4. You don’t even need to worry which goes on which leg, since the entire set is identical.
Cons: If you get the wrong size and can’t tighten them enough around the pastern, they will slip over the hoof. If the pastern velcro gets dirty or starts to wear out, they will come off easily. This is only my second season using them, but I don’t think they will hold up quite as long as my previous Kensingtons. But for the price, I feel like I got my money’s worth.
Prior to using Shoo Fly Leggins, I was using Kensington Fly Boots. I also like those quite a bit, but I like the Shoo Fly Leggins more.