Review on 📏 EMI Basix Economy Digital Caliper Ruler by Johnny Snyder

After a month of using a caliper this product really works. My only criticism is that the bolt at the top of the caliper doesn't tighten properly. You can see in my photo I took it doesn't match the bottom of the legs. You can unscrew the screw and it still retains its stability. So the screw actually has no function. It still retains its stability so you can measure regularity. Useful ECG ruler. I use it to measure PRI, QRS and QT. The markings below for speed are confusing. I don't know how to measure the speed on the rhythm for this ruler. It would be nice if instructions were included with this product.