Chris D.wrote a review of NiteRider Sabre 50 Tail Light on October 28, 2016
Familiarity: I've put it through the wringer
I don't know what the 1 star review is talking about. To turn it off you simply hold down the power button for three seconds and it shuts down. There are three settings--the brightest setting
(all 50 lumens) will give you battery life for an hour+. I mainly keep it on the lowest setting (still really bright IMOP) and it will last me at least 5 hours of biking. It's easy to recharge and it takes about 1 hour to get fully charged. Easy to take on and off of the bike. Overall, pretty happy with my purchase.
Disclaimer: I bought this device from a LBS not from Backcountry.