Well, the illuminator died a while back. I have a new one on order from Anacortes. But I like the battery that replaces both of the smaller ones with one large one. Let me see if I can dig one up out of the drawer.... digging... digging... digging... Ah! here they are!

Duracell 1/3 N 3v DL1/3N/2L76/CR1/3N <- This is the one that only requires one battery

Otherwise I use 2 Duracell 303/357 or 1.5v 303/SR44/SR47/A/J