Hydrofarm JumpStart JS6120 Windowsill Seed Starting Heat Mat and Tray Kit Everything you need to start a windowsill garden using the Jump Start Windowsill and Heat Mat and Tray Kit The kit comes with the Jump Start Windowsill Heat Mat that fits perfectly underneath the two greenhouses Each mini greenhouse features 12 peat pellets The 3" x 20" heat mat improves germination by warming the root area The included Jump Start's vented dome creates the perfect environment for your plants