The ROI-E680 is the ideal balance of size and performance for the seasoned hobbyist and professional growers alike. The E680 is a more compact and lightweight fixture accommodating cultivation with modest space availability, tents, vertical gardens and any commercial application facilitating 4x4 canopies. The ROI-E680 is a very powerful device and a proven versatile workhorse in any type of garden, producing heavy yields and top quality harvests. Grower's Choice does recommend the E680 be utilized with CO2 supplementation to promote a healthy cultivation and the largest yield potential. Without utilizing CO2 the grower might be presenting more light than the plants can process, possibly causing stunted growth or light damage. Know your garden and provide light appropriately.