Well, I disagree a bit. I have the 25 (or 27 foot? can't recall) version of the Zoomed cable. I have it run on the INSIDE of a plastic cage, zigzagged on the ceiling and back, held on with tie-wraps up top, and suction-cups in the back. This is for a GTP who doesn't mess with her cage much.
It works great for heat! I have it in a BARRs cage, which are made to have belly heat, but unfortunately the plastic on the sides and back is thicker. Good for keeping the cage insulated, but bad if you want to try and stick a UTH to the outside back wall of the cage. Since my GTP hangs out on her perch, belly heat wouldn't cut it.
The way I have it (on a thermostat, of course), it seems to work great. The cable at it's hottest seems to get very warm to the touch, but not hot enough to melt plastic or burn an animal (but who knows if it malfunctions...) It's very flexible and waterproof. I'd recommend it where Flexwatt just won't work. It's supposed to be safe to wrap around perches and branches (the perches in the cage are removeable and I didn't want the snake directly ON the cable, so I didn't do that). I have heard of people running it on the inside of pvc plastic perches.
But anyway - it works for certain situations. I wouldn't ever use it without a thermostat though (just like any other heat device for reptiles).
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Lauren Madar - OphidiaGems.com
1.0 Ball Python, 1.1 Hog Island Boas, 1.1 Hypo BCI, 1.1 Surinam BCC, 0.1 Green Tree Python