The Magnum XXXL 6 Inch Air Cooled Reflector is one of the most popular grow hoods on the market today. It is a monster of a hood at 38 x 29 x 10.5 inches but it really spreads the light out so evenly it has become a grower favorite. This one is a 6 inch air cooled model.
Because of its size you would probably want to use the 8 inch magnum if you were using more than 1 hood in a line.
Also this is not the cheapest reflector you can buy to cover a 4 x 4 area and considering that it weighs 35 pounds you will want to make sure you hang it well. This probably is not the best hood for a grow tent because of the weight.
Magnum XXXL 6 Inch Air Cooled Reflector