First off, this product works as intended.  The product itself isn't necessarily the problem when used with an appropriate sized vivarium in a properly heated room, which is what it is designed for, since reptiles require specific conditions.  So this isn't a knock on the product, I am yet to find a Zoo Med product that didn't work as it was meant to.

With that in mind, you must know that this product is designed to work best with enclosures UP TO 50 GALLONS.  Nowhere in the product description is this stated.  We have a custom built 68 gallon wooden enclosure with a plexiglass front door, floor, and a screen top covered two-thirds of the way with plexiglass for heat and humidity control.  As temperatures began to decline with the season, we had to provide supplemental heat for our Ball Python to assist the under the tank heating pad and provide him with a basking spot and adequate ambient air temperatures.  We had a 100 watt Zoo Med infrared bulb in a 5.5 inch Fluker's ceramic clamp lamp, and that bulb would heat the warm side of the cage to 78-80 degrees at floor level.  Our Ball Python would regulate himself appropriately, and would even bask, so we knew that this was perfect for him.  We assumed that a 100 watt ceramic heat emitter would be perfect.  However, we installed this and it would only heat the cage to about 76 degrees, barely within the recommend temperature range for a Bally Python.  Keep in mind that this was in a cage with wooden and plexiglass walls, both of which are better insulators than glass. The reason for this is that with the bulb, infrared light/heat was emitted in all directions and the dome would bounce back everything into the cage, thus it made the bulb heat more efficiency.  With this 100 watt ceramic heat emitter, this effect didn't occur, as the heat is emitted only from the flat portion of the unit.  So, any heat that rises beyond that escaped through the vents in the ceramic lamp and was lost.

In conclusion, do not use this on any enclosure larger than 50 gallons.  Go up to the next step and get the 150 watt model.  If you buy a 150 watt bulb, make sure that your ceramic lamp is rated for a 150 watt unit.  If not, get yourself a new one.  Purchase one with a dimmer switch built in so you don't overheat the cage.  Or, as an alternative to a rheostat/dimmer switch, you can choose to buy a basic 150 watt ceramic lamp, and go to your local hardware store and pick up a dimmer switch cord.  This will also allow you to control the heat/light entering the enclosure.

Three out of five stars, not because the product doesn't work, but because the description lacks important details that every buyer must know.  I hope this review helps someone, since we sacrificed time and money to learn the hard way.
First off, this product works as intended. The product itself isn't necessarily the problem when used with an appropriate sized vivarium in a properly heated room, which is what it is designed for, since reptiles require specific conditions. So this isn't a knock on the product, I am yet to find a Zoo Med product that didn't work as it was meant to. With that in mind, you must know that this product is designed to work best with enclosures UP TO 50 GALLONS. Nowhere in the product description is this stated. We have a custom built 68 gallon wooden enclosure with a plexiglass front door, floor, and a screen top covered two-thirds of the way with plexiglass for heat and humidity control. As temperatures began to decline with the season, we had to provide supplemental heat for our Ball Python to assist the under the tank heating pad and provide him with a basking spot and adequate ambient air temperatures. We had a 100 watt Zoo Med infrared bulb in a 5. 5 inch Fluker's ceramic clamp lamp, and that bulb would heat the warm side of the cage to 78-80 degrees at floor level. Our Ball Python would regulate himself appropriately, and would even bask, so we knew that this was perfect for him. We assumed that a 100 watt ceramic heat emitter would be perfect. However, we installed this and it would only heat the cage to about 76 degrees, barely within the recommend temperature range for a Bally Python. Keep in mind that this was in a cage with wooden and plexiglass walls, both of which are better insulators than glass. The reason for this is that with the bulb, infrared light/heat was emitted in all directions and the dome would bounce back everything into the cage, thus it made the bulb heat more efficiency. With this 100 watt ceramic heat emitter, this effect didn't occur, as the heat is emitted only from the flat portion of the unit. So, any heat that rises beyond that escaped through the vents in the ceramic lamp and was lost. In conclusion, do not use this on any enclosure larger than 50 gallons. Go up to the next step and get the 150 watt model. If you buy a 150 watt bulb, make sure that your ceramic lamp is rated for a 150 watt unit. If not, get yourself a new one. Purchase one with a dimmer switch built in so you don't overheat the cage. Or, as an alternative to a rheostat/dimmer switch, you can choose to buy a basic 150 watt ceramic lamp, and go to your local hardware store and pick up a dimmer switch cord. This will also allow you to control the heat/light entering the enclosure. Three out of five stars, not because the product doesn't work, but because the description lacks important details that every buyer must know. I hope this review helps someone, since we sacrificed time and money to learn the hard way.