Our modular Stack-n-Grow Light System lets you decide the perfect amount of growing space for your needs - and this 2-Tier System helps take your indoor growing to the next level right away! Whether you're a seed-starting savant or a houseplant hero, 2 tiers of full-spectrum light provides plenty of growing room. And when you need more, you can level up by stacking an Add-On Unit on top! Each tier of this Stack-n-Grow system is equipped with 2 full-spectrum T5 fluorescent bulbs (4 bulbs total) that are spaced for optimum light coverage, and super easy to raise or lower. High-tech reflectors direct light down onto plants for healthier growth and less glare. At only 7 lbs., each Stack-n-Grow tier is super lightweight - but sturdy enough to hold up to 110 lbs. System assembles quickly, without tools, and stores compactly when not in-use. Includes wall brackets for added stability. Height Extenders are also available to increase headroom and vertical growing space between tiers. The modular Stack-n-Grow Lights System is as easy as 1-2-3! Start with 1 tier: Stack-n-Grow Lights - Base Unit Or jump right to 2 tiers: Stack-n-Grow Lights - 2-Tier System Add more tiers up to 3 levels: Stack-n-Grow Lights - Add-On Unit Important: When stacking units, prevent water from dripping from upper shelves onto the light fixtures below by placing our Small Boot Trays underneath, or use other drip trays or saucers on each shelf.