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-incn ( 50mm opening ) , please buy this paper. Otherwise buy from this link http://www.bpmonitordepot.com/57mm-roll-thermal-paper-for-contec-ecg80a/ | 