Sure to Grow - Storm Series - Tempest / 4.75"x 4.45" (12/Pack) Non-wicking design allows the grower to feed more often, leading to a healthier plant and better harvests Open cell design allows for air to move freely through the insert, ensuring the stem stays dry and healthy and the roots beneath receive ambient circulation All STG products are pH neutral and require no conditioning or continuous adjustment of your bath due to media influence All STG products are inert and impart nothing to your nutrient solution. This allows the grower to "start from scratch" when developing a feeding schedule Perfect for hobbyists or hydroponic business purposes