describe: High-quality ECG calipers: Made of high-quality metal materials, used to measure ECG waveforms. Adjustable length: The end point can be adjusted to the required length as needed, accurate and stable. Accurate measurement: A ruler is attached to the plastic protective cover for easy measurement reference. Adjustable Tightness: Adjustable screws are used to loosen and tighten the arms. Easy to carry: The protective cover with plastic clip easily attaches to the nursing garment. material: metal color: blue Package Contents: 2 x EKG calipers Contains only the above package contents and does not include other products. Note: Lighting and different monitors may cause the color of the item in the picture to be slightly different from the actual item. The measurement allowance is +/-1-3cm.