This is super easy to change. Literally less than 5 minutes once freezer s defrosted and you’ll be so happy u didn’t buy a new fridge or waste money on repairman.The first one I ordered the heaters were too short. Serves me right for going by a picture. The part number for the smaller version ends in 442. The larger one (No doubt for a 25 Cu.Ft refrigerator) ends in 443. It pays to measure and check sizes. I first replaced the defrost timer which is what usually fails. When the timer didn't fix the defrost I found it was the heaters that were defective. Replacement on my GE refrigerator was easy. First, turn the cold control to OFF. Don't disconnect the wall plug as you will want the freezer light to be working. After removing the shelves and drawers in the freezer, five Phillips screws remove the rear panel. You will probably find the cooling coils heavily iced. I put a small electric heater on the freezer floor and closed the door. Thirty minutes later the ice was gone but the drain pan underneath was overflowing. What a mess! Notice how the heater wires are dressed so you can dress the new wires the same way lest they get pinched behind the panel. Remove the two screws holding each heater and unplug the connector. Install the replacement heaters and dress the wires exactly like the originals were. Plug in the connector making sure the wires are not in contact with the light bulb. Make sure the edge seals are on the panel correctly and install the panel, the shelves and the drawers and turn the cold control back to it's usual setting. Buying the defrost heaters and timer from Amazon saved me more then $100.00 over prices at our local parts supplier. By installing the parts myself I figure I saved $200.00 over paying for a service call. Give it a try. All you really need is a Phillips screw driver and you can't really make it any worse.Purchased this unit to go into a GE Profile TFH30PRT-AWW. It fit like a glove and worked flawlessly for 3 months, until it didn't. There is a thermal switch in the assembly that attaches to the evaporator coil and opens the circuit once the coil has been warmed sufficiently irrespective of the defrost timer. That switch failed open circuit so no more heat. The unit was new, unused, in pristine condition. It appeared to be a manufacturing/infant mortality issue rather than anything to do with the vendor. I contacted the vendor through Amazons vendor email contact system and they had a new unit on the way to me that day, no charge. Can't ask for better than that. The second unit, like the first was new, shiny with factory packaging. The packaging did not say GE anywhere but it is visually identical in appearance, wire color/grade and molded connectors to the original unit that came with the fridge.I knew I had trouble when the freezer section of my GE Profile side by side refrigerator started icing up. I knew I was in real trouble when the refrigerator never turned off and the temperature seemed to rise. I was resigned to buying a new refrigerator but after googling the problem I realized it had to be the defrost timer or the defrost heater. After turning off the refrigerator and waiting 24 hours to take the inside back panel off I found the freezer coils completely caked in ice. This defrost heater was an exact replacement for the existing one and even included the temperature sensor. All I had to do was undo some screws, install the new heaters, plug it into the harness, and snap on the sensor. All is good now and the freezer cools down to zero degrees. I did buy a couple of LCD thermometers so I could monitor the freezer and refrigerator temperatures from now on.Product seems to be workingFineArrived when promised, was genuine GE part, was half the price GE was asking, and the best thing was IT FIXED THE PROBLEM.This is the second set I've bought, they last about a year and a half then the filaments break... (it seems others have had this problem also, maybe it's just the model, issues with the design, whatever). I don't know who's fault it is, but they aren't long term items (usually these things last quite a while, other refrigerator brands / models). I do not think there is a "correct and longer lasting" source, I think it's just a bit of a snakebit engineering / physical scenario. If you've got a bit of an older GE frig these things fit, it's just what you've got to do, when they need replacing... unfortunately.todo perfectoI ordered the first time and I had to return it because it was defected and I bought a second one thinking that it will work but unfortunately it worked only till after the return window closed right after 35days.Very unsatisfied