Just spotted this and seen that it got a fair bit of heat last month and this is a tiny bit cheaper at only £19.95.
It ships from china (despatches within 24hrs according to the info on the link) so should get here in time for Christmas if you're thinking of buying as a gift.
There are 2379 pieces quoted as being in stock at the time of posting so plenty to go round BUT this price is advertised as a "flash sale" and so will expire and go back up 34% in price in 4days and 3hrs or so from now.
I don't know much about this item but I've copied some bumf below from the info on the link.
Mi Band 2 is a smart watch bracelet for you, especially for sports lovers!
Do you know how many steps you take, how many calories you consume, and how far you run? Don't worry, when you wear the bracelet to do exercise, such as running, climbing, all these data can be synchronized and analyzed on your mobile phone which helps you plan your exercise time and amount more reasonably. It comes with TPU adjustable wristband, giving you a skin-friendly, breathable feeling. When you sleep, it will monitor your sleep. It can also wake you up by vibrating gently.
Mi Band 2 record every moment staying with you. Just to live a healthy life with it!
- Bluetooth Synchronization
With Bluetooth 4.0, this smart watch is available for smartphones with Bluetooth functions.
- OLED Touch Screen
Just touch the circular button gently, the OLED screen will display current time, steps, heart rate, distances, calories, etc.
- Heart Rate Monitor
It can dynamic-static monitor your heart rate, provide data for you at any time.
- Incoming Calls / APP Message Alert
When someone calls or sends any messages in your phone, the watch will remind you via vibrating, so you will never miss them!
- Sleeping Monitoring
Accurately monitor total effective sleeping time and motions time every night, also APP will give you periodical evaluation, help you develop good living habits.
- Sport Monitoring
This smart watch can record steps, calories and distance. Let you know your sports data, adjust your exercise program and get a healthier life!
- Intelligent Alarm Function
Wake you up every morning, will not be late for work; idle alert to remind you with vibration, stretch your legs after working for a long time.
- No Passcodes Required
Every Mi Band 2 have an exclusive ID, when your smartphone closes with the band, your phone will be unlocked, just identify yourself with Mi Band 2.
- IP67 Waterproof
The IP67 waterproof allows the bracelet to be held in the water for a maximum of 30 minutes at a depth of 1 meter. ( Don't wear the bracelet when diving )
- Full Compatibility
Support Android 4.4 or above and iOS 7.0 or above with Bluetooth 4.0.
- Download APP
You can search the name "MI FIT" in the "App Store" or "Google Play" to download the APP combined with Mi Band 2 to enjoy happy sports time.
Bluetooth version: Bluetooth 4.0
Language: English,Simplified Chinese
IP rating: IP67
Screen type: OLED
Operating mode: Touch Screen
Compatible OS: Android,IOS
Compatability: Android 4.4 / iOS 7.0 and above system
People: Female table,Male table
Available color: Black
Type of battery: Lithium polymer battery
Battery Capacty: 70mAh
Standby time: 20 days
Charging time: About 3hours
Functions: Alarm Clock,Call reminder,Measurement of heart rate,Pedometer,Sedentary reminder,Sleep management,SMS Reminding,Steps counting,Time
Alert type: Vibration
Dial and Band
Shape of the dial: Elliptical
Case material: Plastic
Band material: TPU
Weight and Size
Dial size: 4.03 x 1.57 x 1.05 cm / 1.59 x 0.62 x 0.41 inches
Band size: 23.5 x 1.05 cm / 9.25 x 0.41 inches
Wearable length: 15.5 - 21 cm / 6.1 - 8.28 inches
Product weight: 0.017 kg
Package weight: 0.140 kg
Product size (L x W x H): 22.50 x 1.57 x 1.05 cm / 8.86 x 0.62 x 0.41 inches
Package size (L x W x H): 10.00 x 10.00 x 3.50 cm / 3.94 x 3.94 x 1.38 inches
Package Contents: 1 x Original Xiaomi Mi Band 2 Smartband, 1 x Original Band, 1 x Charger Base
edit - use code MibandBF and drops to £18.11 - Goonertillidie