traditional Tibetan lock has beautiful ornamentation on key and lock.
key size 13,3 cm (without ring), width: 5,3 cm
lock: 8,1 x 7,3 x 3,8 cm

ladak monesrty lock

In the bigger Tibetan monasteries only a small percentage of monks were really studying and persuing enlightenment.
Many monks had worldly duties: extract taxes, being guards of Lamas, shrines, temple or monastery gates, accompany monastic caravans etc.
Those monks needed weapons - but by their monk vows they were not allowed to have blades/ knifes/ swords.
Such a iron key strung to a half to one meter leather string was a perfect weapon to crush assailants heads.