This book presents the advanced instructions on the practice of Bonpo Dzogchen as per the Zhang-Zhung tradition of Tibet. It contains the English translation of the root text and its commentary of The Twenty-one Little Nails, belonging to the fourth cycle of the Zhang-Zhung Nyan-gyud collection.

It focuses on the fruit or result of Dzogchen practice, and in particular on the removing of doubts with regard to the Natural State of the Nature of Mind being the source of the Thodgal visions experienced in practice. Also included in this volume are the Tibetan of the root text in transliteration and further annotations to the transliterations drawn for the extensive oral explanations of Yongdzin Rinpoche given on a number of occasions.