The Four Nails སྲོག་སྡོམ་གཟེར་བཞི Sok Dom Zer Shi

The four nails or “four nails that secure the life-force of the practice” (Tib. སྲོག་སྡོམ་གཟེར་བཞི་, sok dom zer shyi, Wyl. srog sdom gzer bzhi), an important aspect of kyerim practice, are:

The nail of all appearance as the deity (nangwa lha yi zer) or the nail of concentration (samadhi) on the deity (ting nge dzin lha’i zer) or (kyerim lha'i zer)
The nail of all sound as the mantra (dra drak ngak kyi zer) or the nail of the essence mantra (nyingpo ngak kyi zer)
The nail of the activity of emanation and absorption (tro du trinlé kyi zer)
The nail of the unchanging wisdom mind (gongpa mingyurwé zer)
According to Nyoshul Khen Rinpoche, these four points were first taught as a special mengak by Guru Padmasambhava in the Kagyé Deshek Düpa.