We take cryptocurrency — so the coins you hold can buy real hardware.Pay in crypto, spend it on real hardware. Free insured shipping worldwide over $399. Plain, unbranded boxes, sent from Germany.Free insured shipping over $399. Your rate is locked for 30 minutes once checkout opens.Rate locked 30 minutes. Every item sealed, serial-checked and covered by a 24-month warranty.Sealed, 24-month warranty.

Saved items Sign in
Black round smartwatch with silicone strap and aluminium case

allentian

allentian C21 smart watch black 28 mm 170 g

SKU CH-BQ5N-TBHM5

Bluetooth calling smartwatch with health tracking, sleep monitoring and multi-sport modes in a lightweight aluminium case

  • ColorBlack
  • SizeMedium
  • CompatibilityAndroid / IOS
  • Sports TeamNO
  • Bluetooth calling keeps you hands-free
  • 170 g lightweight build stays comfortable all day
  • Multi-sport modes track every workout
  • IP67 rating handles rain and splashes
  • Battery lasts up to 7 days per charge

Compact wrist companion

The allentian C21 is a lightweight smartwatch built for daily wear and basic fitness awareness. Its 28 mm round aluminium case weighs 170 g and secures with a classic silicone buckle strap. Touch and button controls pair with Android or iOS phones to deliver step counting, sleep monitoring and intelligent reminders. It suits users who want essential tracking without a bulky device.

Daily thermal and power profile

Magnetic charging keeps the routine simple while the TFT screen and low-power platform target a battery life of less than seven days under normal mixed use. Life-waterproof construction handles sweat, rain and hand-washing without extra bulk. No active cooling is present, so the watch runs silent and stays cool against the skin throughout the day.

Sustained activity behaviour

During continuous sport sessions the multi-sport modes log data while the small case limits onboard sensor space. Bluetooth calling and music playback draw extra current, so multi-day endurance drops noticeably when those features stay active. Buyers who need multi-week battery autonomy or advanced health metrics should look elsewhere.

Highlights

  • Bluetooth calling keeps you hands-free
  • 170 g lightweight build stays comfortable all day
  • Multi-sport modes track every workout
  • IP67 rating handles rain and splashes
  • Battery lasts up to 7 days per charge

Specifications

ColorBlack
SizeMedium
CompatibilityAndroid / IOS
Sports TeamNO

Questions about this item

How do I pair the C21 with my phone and what step is often missed?

Enable Bluetooth on your Android or iOS device, open the companion app, then confirm the pairing request that appears on the watch screen — skipping that on-screen confirmation is the step most people miss.

Which part of the C21 will need replacing first with daily sport use?

The silicone strap with classic buckle will show wear before the aluminium alloy case, so plan to replace the band when it stretches or the buckle loosens.

What stops me from using the C21 continuously during a long outdoor trip?

Battery life is less than seven days, so you must bring the magnetic charging cable for any trip longer than a week.

Also in this aisle

People compared these

Same shelf, same checkout — eight coins and a 30-minute rate lock.