If you have one of these from the BPL store or elsewhere -
From the manufacturer
"StarFlash Ultra Water Immersion Notice 10.27.08
UST has observed a decrease in mirror performance in the rare situation where the StarFlash® Ultra™ mirror is immersed in water for extended periods of time. After our testing is complete, letters will be sent to Ultra™ customers regarding the water immersion findings. Production on the Ultra™ mirror has been halted while engineered solutions are quantified and verified. Our former long-standing StarFlash® signal mirrors will be offered in the interim."
Doug Ritter and Company discovered this, and in some cases the effectiveness of the mirror fell off dramatically. Not all mirrors say Ultra, but the frameless style is definitive. Details are found HERE.