Package & Size:Package include 3pcs EKG calipers measuring tool, meets your measurement needs; EKG Calipers Length: 11.5cm/4.5inches (from top to points)Professional EKG Caliper: Measuring tool made with high brass materials for measuring electrocardiogram wave sectionsAdjustable Length:End points are adjustable to the length for you . Super and stay steadyEasy to Clip: Protective cover with a plastic clip that is easy to attach to a nursing uniform; Lightweight and durable, easy to carry around Measurement: Protective plastic cover includes a ruler for easy measurement referenceMaterial: metalColor: as shownPackage Contents:3 x ECG caliperOnly the above package content, other are not included.Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.