The four nails or “four nails that secure the life-force of the practice” (Wyl. srog sdom gzer bzhi; Tib. sok dom zer shyi), an important aspect of kyerim practice, are:
- The nail of all appearance as the deity (nangwa lha yi zer) or the nail of concentration 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.
- Four stakes that bind the life-force (Dharmachakra Translation Committee)