Post Office Bank Book
For many years the NZ Post Office was the only real option for ordinary people to bank their money - every community had a post office and all government type transactions could be conducted there. Schools had a post office saving scheme and school children were encouraged to deposit some money every week. Each transaction was hand written in ink, and stamped.
The trading banks did not operate similar passbook savings accounts until the early 1960's when there was a law change. For more information see https://www.bnzheritage.co.nz/archives/story/the-start-of-bnz-savings