How do they work??? I've seen some similar products in the past but they were basically nothing more than a fancy strong light... where it basically just illuminated the nail so that you could see the quick easily. But never heard of something that "detects" the quick...
ETA: Ok so I just found it on Amazon and the reviews are pretty bad... plus it says right in the product description that "Designed for use on small animals, cats, small and medium dogs up to 40 lbs. unless nails are dark and dense" & "Not recommended for large dogs or dogs with dark, dense nails." I would think that the whole point of marketing these is for people who's dogs have dark nails and have trouble seeing the quick.
There are 24 reviews, and they got less than 2 stars out of 5. Here's the link in case anyone wants to see.