I bought this years ago before I became a tobacco farmer wan-a-bee. What I like about this compared to the more common heat mats is that it has the thermostat controller already wired into the mat and it comes with a 3 ft wire with the heat probe on the end. When I set my float tray into the water I just place the probe under the tray (submerged in the water). I can keep my water a constant 70 to 110 degrees. A conventional heat mat does not work with a float tray becasue it does not have enough wattage to pentrate the "box" that your float tray is in.In my case my box 's bottome is 1/2 inch plywood. They seem to be pretty pricey now. I paid much less when I bought mine.
http://www.harrisseeds.com/storefront/p-14532-heat-mat-agritape-22-in-x-10ft-wscreen.aspx
http://www.harrisseeds.com/storefront/p-14532-heat-mat-agritape-22-in-x-10ft-wscreen.aspx
