my grow room is a box 4 feet wide by 4 feet tall by 2 ft deep. a light bulb releases light in every direction, with reflectors u can control where the light goes.. so if the reflector sits above the light, all the light that would naturally go up goes down instead, i have tin foil on my walls and tinfoil on the inside of my reflectors. in my grow the reflectors did a lot. soon as i put them in my plants got bushy but i was also lsting