The ROI-E680 is the perfect balance of size and performance for the proficient enthusiast and professional growers alike. The E680 is a more compact and lightweight fixture suited for cultivation with modest space availability, tents, vertical gardens and any commercial application facilitating 4x4 canopies. The ROI-E680 is a very effective device and a proven versatile workhorse in any garden, producing heavy yields and top quality harvests. Grower's Choice does suggest the E680 be utilized with CO2 supplementation to support a healthy cultivation and the greatest yield potential. Without using CO2 the grower may be introducing more light than the plants can handle, possibly causing stunted growth or light damage. Know your garden and provide light accordingly.