Penguin Pocket EKG Calipers are ideal for all healthcare students and professionals learning, teaching or reading EKG tracings or rhythm strips. Designed and manufactured in the United States, these EKG calipers are stylish, adjustable, and made from lightweight materials for daily use. Measure QRS complexes, PR intervals, and irregular tracings with pinpoint accuracy. Each caliper comes with laser precision tension controlled legs and fine point brass tips for accurate EKG reading and evaluations. Adjust the caliper leg tension tighter or loosen them (with the included wrench) to have complete control of your calipers.