Hydrofarm's Commercial Heat Mat helps maximize your growing area by letting you daisy chain up to 4 of the MTMDA add-on units to this one.

Bottom heat is one of the most important and effective ways to improve germination and rooting. Our new HEAVY DUTY modular commercial heat mats will provide uniform heat for hundreds of seedlings or cuttings.

• Supersized mats: 60" x 21"
• Rugged and durable with waterproof connectors
• Daisy chain up to 5 units (4 add-on units plus the the Commercial Mat)
• Plug into our Digital Heat Mat Thermostat (MTPRTC)
  (required, sold separately)

http://www.hydrofarm.com/downloads/fc/Commercial%20Heat%20Mat%20and%20Add-On%20unit_23682.pdf