DetailsExcellent low perfusion ≤0.4%. Accuracy ±2%. 2.Visual alarm (all models) and audible alarm (A4) function . 3.Low power consumption. 50 hours continuous to work . 4.Low voltage indication . 5.Small and light weight, convenient to carry. No key design. Patent 4 direction auto-orientation . Ø Automatic power on and off . Ø Varietal color for your option (Green, Pink, Royal blue and Black