I ran this test using the bulb I have for my beardies. I will be running this test again with the Powersun 100w bulb I have as well. 48" Arcadia 12% HO bulb: No screen: 6 inches 340; 12 inches 180 Window screen against bulb: 6 inches 218; 12 inches 113 1/8" screen against bulb: 6 inches 280; 12 inches 141 1/4" screen against bulb: 6 inches 337; 12 inches 178 Based off this data the following is allowed percentage through each type: At 6 inches to basking spot: No screen: 100% Window screening: 64.12% (Blocked 35.88%) 1/8" Reptile screen: 82.35% (Blocked 17.65%) 1/4" Reptile screen: 99.12% (Blocked 0.88%) At 12 inches to basking spot: (This is relative to 12" measurement only (not compared to 6") No screen: 100% Window screening: 62.78% (Blocked 37.22%) 1/8" Reptile screen: 78.33% (Blocked 21.67%) 1/4" Reptile screen: 98.89% (Blocked 1.11%) I hope this helps people when deciding what kind (if any) of screening to choose for their reptile tops. I also found when looking at different bulbs (including the Powersun, Zilla Desert 10.0, and ZooMed Reptisun 10.0), that the Arcadia provides the closest to real sun UVB levels. I know that you can't directly compare the numbers from the Solarmeter 6.2, but they have substantially higher output of UVB levels read by the meter. I would suggest anyone looking into new bulbs, check out lightyourreptiles.com and talk to Todd. Their fixture also includes a nice reflector built in to it. I got my tester and light from there at better prices than anywhere else. Again, that's the bulb and fixture I used for this test.