6) We need a battery box to hold the 4x AA cells. I’ve used a box from an old Petzl MYO head torch, but a box from a Petzl DUO or equivalent could be used instead. I have removed the wires from the lamp end ensuring the remaining wire is long enough to reach round a caving helmet.

7) Reuse the grommet from the original cable to ensure a good seal between the new cable and cap lamp.