The ROI-E680 is the ideal balance of size and performance for the experienced enthusiast and professional cultivators alike. The E680 is a more compact and lightweight fixture accommodating 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 functional workhorse in any type of garden, producing heavy yields and high quality harvests. Grower's Choice does suggest the E680 be utilized with CO2 supplementation to support a healthy cultivation and the largest yield capacity. Without utilizing CO2 the cultivator might be introducing more light than the plants can process, possibly causing stunted growth or light damage. Know your garden and supply light accordingly.