The sac is a bag for money protection . In the past this sac did not have a specific value of gold and silver coins to be recognized by the people . During the French Campaign in Egypt the sac value was specified and estimated at 25000 half-Fadda which is equivalent to 625 piastres and in the reign of Muhammad Ali it was estimated at 20000 half-Fadda which is equivalent to 500 piastres .