minimal capacity of at least 3ml of indelible ink sufficient enough to use over 500 times on voters. Silver nitrate density between 14% and 25%. Dries in less than 30 secondss. The ink must not contain any dangerous substance on the users. The ink has to resist at least 10 hours regardless the washing by water or soap etc. Hermetic packaging to protect the product from any possible exterior factors. 10 psc in a pocket