Features: 1. Step ruler: Designed using a scientific 7-step electrocardiogram interpretation method, providing clear and intuitive reference points for difficult to remember key points, and gradually following the entire process Helps to quickly analyze electrocardiograms. 2. Portable Transparent Design: This must-have electrocardiogram ruler is made in ID sized transparent format and can seamlessly fit into a badge clip, pocket, or tool kit, ensuring quick access anytime, anywhere - perfect for use anytime in the workplace, classroom, or clinical environment. 3. Easy to read reference: This reference card allows you to measure heart rate and check if the PR interval, QRS complex, QT interval are outside the normal range, as well as ST segment elevation/depression. The electrocardiograph ruler will be an excellent addition to your ID badge. 4. Durable and high-quality materials: This ECG/ECG 7-step ruler is made of sturdy and transparent materials that are wear-resistant, waterproof, and easy to clean. It can maintain its clarity and functionality even after long-term use in demanding environments. 5. Very suitable for learning and practice: An essential tool for electrocardiogram education and practice, not only suitable for healthcare professionals, but also for anyone who wants to master electrocardiogram interpretation. Specifications: Material: Plastic Product Weight: 15g Size：8.6x5.4cm Package Include: 1x Ruler