Microfilm of Om Mani Padme Hum
2,688 mani mantras per page.
2 pages per frame on the microfilm.
Approximately 250 frames per pendant insert (usually more).
Approximately 1,343,000 Om Mani
Padme Hum mantras per pendant insert.

The mantra originated through a process begun by Lama Zopa Rinpoche
when he asked me to write to His Holiness the Dalai Lama to request
a corrected version of Om Mani Padme Hum written in Tibetan.
There was some question as to how the "ni" in Mani is written.

Revolving prayer wheels.
If you look closely you can see that there are two pages per frame. To see the individual mantras you need a microscope.
Om Mani Padme Hum - Tibetan script

Inserts are taken from a large core or pancake of microfilm then wound by hand into prayer wheels. (This photo shows a microfilm pancake with rainbow syrup).

This prayer wheel is all microfilm. (64 billion mani mantras). The microfilm is protected with colored electrical tape and should last a couple of centuries.
This dharma wheel has an inner core of microfilm that extends out to approx 19 inches then has paper mantras that have strips of cloth between each row protecting them. (Total mani mantras: approx. 12 billion).

This is our electric mantra roller with revolving feeder.