Several of us have tested BR goggles, testing the output with a pass through goggles and without, of our BR lasers on our Laser Power Meters, and have found about 1 t0 2% of most BR's, (which of course vary in wavelength, (405nm +/- 10nm or (thereabouts) , which although not "Official" is about OD2.  I see a bigger filtering of BR light w/ the red lens,btw, but I like the yellow best for easy viewing of subtle florescence, and have sold 2 pair to a cancer research facility that also bought 2 BR lasers to identify tumor boundaries in lab mice, so I am pretty confident these protect well and show more easily what "glows", however for those with >250 mW a bit more safety seems to be found using the red lens ones.  
laserdiode, I'll send a PM after I re-check postage to UK  Thanks!  -Glenn