Each and every Stack-n-Grow Light unit features two 3′ long LED lights, engineered to save energy and grow exceptional plants. With this modular system, you’ll start with the LED Stack-n-Grow Light System base unit, after which stack as much as two LED Add-On units on top of the base unit to multiply your growing space. Fast, no-tools assembly Start 72 seedlings in 3-1/2 sq. ft. of space Shown with our GrowEase Seed Starter Kits, sold one by one Easiest-ever system for adjusting light height Lightweight — Each and every unit weighs just 7 lbs. Add-On units include wall brackets for additional stability. Vital: When stacking units, prevent water from dripping from upper shelves onto the light fixtures below by placing our Small Boot Trays (32-709) underneath, or use drip trays or saucers on Each and every shelf. About our LEDs: Our product development team engineered these LED light tubes to meet the exacting needs of plants. They deliver bright, full-spectrum light with an additional spike of blue light to stimulate stronger root growth and strengthen photosynthesis. LED tubes may not shatter like glass bulbs and they are mercury-free so, unlike fluorescent bulbs, there is no need for special disposal.