I'm installing an ACK ELT my RV-12iS project. The ACK instructions mention Duracell lithiums for the audio alert and remote switch boxes and that's still what is shown in the photos. But the small print says to see ACK Installation Advisory IA E-04.6 on their website. That advisory says that Duracells tend to leak and cause mayhem. They provide a long list of alternatives. I have done a couple of ACK installations in the past few years and the Duracells are coming out ASAP. There has been mention on VAF of Duracells leaking but this is the first I had heard of a specific recommendation from a manufacturer to not use them.