ECG / EKG Medical Grade Recording Chart Paper, Roll, Gray Grid, 76x25, Equivalent to Philips - HP 989803138181, M3536 and M3535A Fits Hewlett Packard models M3535/A, M3536/A and Heartstart MRX Fits (Sold by the roll, 50 rolls per case) Availability: Usually ships the same business day Philips - HP 9898-03138181, M3535 and M3536 equivalent A113755Regular price: $5.95Sale price: $2.30 Copyright 2006-2011, A1cardiology.com