Forgive me for butting in 
I'm currently using a 100 watt T-Rex active heat "FLOOD" (very happy with it BTW) and I think what they're saying is the "SPOT" versions are better suited to large enclosures. The minimum recommended distance for the 100 watt "FLOOD" is ....6 inches.... so if can place the UV HEAT bulb standing vertically over the cage or on top of the metal screen and the animal is NO CLOSER THAN 6 inches then you're ok. The same 100 watt "SPOT" version has a min distance of -at least- 18 inches which is 3 times the min of the flood version. The spot bulbs concentrate heat into a smaller area. So pointing one into a large enclosure on a basking spot would be its best use.
See the difference? Even the box says the "FLOOD" versions are better suited to the average user. It's mostly a heat concern. Apparently all these bulb types put out UV rays at least 6 FEET for a longer period of time so that's not a concern and it's better for you animal. The fluorescent lights don't get anywhere close to that distance and are no good after about 6 months. These bulbs are probably good for about a year.
I know when I switched to my UV heat bulb my animals where more active and the colors where much better. I have it pointing straight down (apparently they work best in this position) at a basking area which is made of some composite faux stone material. The material is warm to the touch and that's a good thing. I still use the fluorescent fixture just because I have it and I don't want it going to waste.
Min Distances from the T-rex UV heat box:
100 watt flood...6 inches
160 watt flood...18 inches
275 watt flood...24 inches
100 watt SPOT FOCUS...18+ inches
160 watt SPOT FOCUS...36+ inches
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0.0.2 Bearded Dragons(Ziggy and Stardust)