The ROI-E680 is the perfect balance of size and performance for the proficient enthusiast and professional cultivators alike. The E680 is a more portable and lightweight fixture suited for cultivation with moderate space availability, tents, vertical gardens and any commercial application facilitating 4x4 canopies. The ROI-E680 is a very powerful fixture and a proven versatile workhorse in any kind of garden, producing heavy yields and high quality harvests. Grower's Choice does recommend the E680 be utilized with CO2 supplementation to promote a healthy cultivation and the greatest yield potential. Without using CO2 the grower might be presenting more light than the plants can handle, potentially causing stunted growth or light damage. Know your garden and supply light appropriately.