Roger at Sav-On Tackle just bought a dozen of them to see if they sell and work OK. I suggested that he drop one in a bucket of water and see how they do as well as being waterproof. You can check them out at the Promar seminar that will be at Sav-On Tackle next Wednesday at 6pm.
They obviously look like a Chinese product...so I'd be a little weary of buying too many at first.
At 2 for $20...I think I'll stick with the LED light sticks until these new things are proven, and besides it looks like just one more thing to attach to your marker float or main line..."keep it simple stupid" is my motto...!
Good Luck and Stay Safe this Season...!