Mod. 58 is the successor to Mod. 51/52. There are several obvious differences. One is the design of the front pocket, the extension of the skin extends slightly, and the space of the front pocket is slightly increased. Second, the adjustment position of the leather shoulder strap is supported from the waist. The belt moves to the bottom. Others, such as hardware, the location of the name column, etc., have also been adjusted. I should be able to understand what I am talking about when comparing photos. ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ Back panel size: 50 x 40 cm. The error ± 2 cm is within the normal range. With traces of use, each item is slightly different from the details and shipped randomly.