EKG Ruler - Clear by LifeForm $0.00 pn01321 EKG Ruler - Clear / PN01321 / Cart Title EKG Ruler - Clear Product ID PN01321 CheckoutType Cart Add to cart Plastic EKG ruler with standard intervals features charts and black scales. 1-5/8 in." H x 6-3/4 in. W. For instructional use only. Not for human or animal use.