For Contec ECG80A Handheld ECG , there are two version . The early version uses 57mm papler , please double check the Paper compartment of the monitor . If your monitor has 2-1/4 incn ( 57mm opening ) , please buy this paper. Otherwise buy from this link http://www.bpmonitordepot.com/50mm-roll-thermal-paper-for-mindray-recorder-printer-contec-ecg80a/ | 