A new Apple Watch band can detect dangerous levels of potassium in your blood without the use of needles.

KardiaBand takes an electrocardiogram, then uses a specially designed algorithm to identify abnormal patterns. AliveCor says its Apple Watch band can detect hyperkalemia with 94 percent accuracy. Such a diagnosis usually would require invasive blood tests

The Apple Watch just got a whole lot more indispensable! Today, two major heart-related developments mean Apple’s wearable device could one day save your life.

Firstly, Apple teamed up with Stanford Medicine to launch an Apple Watch heart app that looks for deadly atrial fibrillation. It alerts users when they experience irregular heart rhythms, and can actually get them help.

Meanwhile, the Food and Drug Administration finally approved AliveCor’s Kardiaband EKG reader. It’s the first medical device accessory for the Apple Watch.