The ROI-E680 is the perfect balance of size and performance for the experienced hobbyist and professional growers alike. The E680 is a more compact and lightweight device accommodating cultivation with modest 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 kind of garden, producing hefty yields and top quality harvests. Grower's Choice does suggest the E680 be used with CO2 supplementation to promote a healthy cultivation and the greatest yield potential. Without using CO2 the grower might be introducing more light than the plants can process, potentially causing stunted growth or light damage. Know your garden and supply light appropriately.