Maham 4 is a naval limpet mine with possibility of sticking on various ships platforms, different metal and nonmetal structures by a frogman with two methods of permanent magnet and nail shooter. The operating depth of the mine is 1-40 meters. After adjusting the mine’s timer and installing it on an intended place, it is armed with pulling the safety fork by operator, and the timer is activated, then after passing the preset time, the mine will be exploded. For the safety of diver and operator, one safety lock with high reliability has been used in the mine. The timer is a mechanical type which is adjustable with interval time of 10 minutes up to 6 hours. (This time can be changed by user, if necessary).