The Inovonics BAT608 CR2 lithium battery, 0.8Ah rated, is used in the EE1233D, EE1233S, EE1235D, EE1235S, EE1236D, EE1238D, EN1233D, EN1233S, EN1235D, EN1235S, EN1235DF, EN1235SF, EN1236D, EN1238D, ES1233D, ES1233S, ES1235D, ES1235S, ES1236D, ES1238D, FA203D, FA203S, FA205D, FA205S, FA113, FA212, FA214 and ACC631. This battery can be purchased from Inovonics or at many retail outlets.