1.5V battery for TDS-ZT2, TDS-EZ, TDS-3, TDS-4, TDS-4TM, TM-1, COM-80, COM-100, PH-80, PH-200, HMEC-3, HI98121, HI98129, ORP-200, and DM-1 meters. 

Meters that do not display anything when you press the "ON" button need to have their battery replaced.
Battery also known as: 1128MP, 1166A, 208-904, A-76, A613, AG14, AG-14, CA18, CA19, CR44, D76A, G13A, G13-A, GDA76, GP76A, GPA7, GPA75, GPA76, GPS76A, KA, KA76, L1154, L1154C, L1154F, L1154G, L1154H, LR1154, LR44G, LR44GD, LR44H, MS76H, PX76A, PX675A, RPX675, RW82, SB-F9, V13GA
Note: Brand may vary.