Such a simple, effective idea! Just place a jacket around a young plant, fill its chambers with water, and forget about it. The sun heats up the water, which in turn creates a frost-free environment for the young plant, jump-starting the growing season and bringing in the harvest a month or more sooner! Insulating jackets measure 18 by 17 inches, with long, narrow chambers to fill with water. The water holds up the jacket and heats the plant within, keeping the interior environment several degrees warmer than the surrounding air. Perfect for those frosty spring and fall nights that can stall the growth of your vegetable garden! When you no longer need the jacket, simply drain the water, fold the jacket flat for storage, and admire the healthy plant it has protected! You will want to fill your garden with these jackets, which also guard against strong winds and marauding animals that can crush young plants. So simple, so effective! Set of 2.