and high-quality materials: made of sturdy, transparent PVC, this 7-step ruler is wear-, waterproof, easy to clean, and maintains its clarity and function for long-term use in harsh environments. 7-step ruler: Designed using a scientific 7-step ECG interpretation method, it provides a clear and intuitive reference point for those key points that are difficult to remember through a step-by-step tracking process! Helps to quickly analyze ECG. Step-by-step ECG interpretation: It has a well-structured 7-step ECG/ECG interpretation guide with clear reference points, simplifies complex data, and provides auxiliary analysis for beginners and experienced professionals. Portable transparent design: This must-have ruler for families is a transparent format the size of an ID and can be seamlessly inserted into a badge holder, pocket or tool kit to quick access anytime, anywhere-ideal for workplaces, classes and more. User-friendly: The 7-step ruler has a simple and easy-to-use layout, which guides the ECG interpretation process , especially suitable for students and clinicians who need systematic learning or quick review. Quality: 100% New Product Name:ECG 7 Step Ruler Colour:As Shown Material:Plastic Package Contents: 2 * ECG 7-step ruler 1 * Card slot Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.