Petzl - AA Battery Adapter for ZOOM Headlamp The Petzl E13 was designed for the Petzl Zoom headlamp If you purchased the Zoom without an adapter the zoom only runs on Flat 4.5v olt batteries, this is a great alternative. The adapter fits snugly into the battery compartment of the Petzl Zoom and allows you to use 3 standard AA batteries (not included) instead of the 4.5 volt flat battery.