GearBest offers the Xiaomi Amazfit Arc Smartband Heart Rate / Sleep / Activity Tracker in Black for $38.99. Coupon code "DNAMAZFIT" knocks that to $33.99. With free shipping (choose "Unregistered Air Mail" during checkout), that's $6 under our January mention and also the lowest price we could find now by $6. It's compatible with iOS and Android and tracks heart rate, steps taken, distance traveled, calories burned, and sleep quality. Features include a 0.42" OLED touchscreen display, Bluetooth 4.0, smart notifications, clock function, alarm, IP67 water-resistance, and rechargeable Li-ion battery with up to a 20-day life.

Note: This item ships from China and may require three to seven weeks for delivery. Want it a little sooner? Choose "Registered Air Mail - US post" for $1.35 during checkout to receive your item in one to four weeks. The countdown timer on the product page does not reflect an actual expiration time and resets daily.