A combo is a rug with the neck rug actually sewn permanently to the rug, such as this one illustrated. This means you do not need dee attachments on the rug or attachments at the back of the neck rug to hold it in place. It works extremely well in a summer rug set.
Skye Park Summer combos are made with extra length to ensure your horses neck is covered when it has its head down grazing, and are roomy enough to allow air circulation to help alleviate mane rub.
If you pull our neck rug forward as far as you can, yes it will cover your horse's head. Once your horse puts its head down to graze the neck rug will fall back into place and will not come back over the head on its own, but rather settle behind the ears giving maximum protection.