The article provides a detailed analysis of a riveted iron helmet (GIN 148), stored in the Akmola Regional History Museum (ARHM), Kokshetau sity, Republic of Kazakhstan. Initially the helmet was determined as "Russian" by Kazakh researchers and later it was re-classified as a "Kazakh helmet". The typological analysis conducted by us has provided the date and the attribution of the helmet more precisely. The helmet belongs to the class of iron helms by its material, to the riveted class by the design of the crown and to the spheroconical type by shape of the dome. Total height is 24.5 cm., the diameter is 21.0 cm. The crown of the helmet is riveted from four plate-sectors, splices of which are covered with narrow overlays with a flat edge and a stiffener (the width of overlays is approximately 1 cm). The helmet is encircled by two narrow iron hoops at a certain distance from each other. A kind of "skeleton" of the helmet is formed from the upper hoop together with the vertical overlays covering the splices of the crown plates. The latter strengthen the construction of the helmet and protects its most vulnerable places - the docking seams of the crown plates. So-called "box" visor (width - 1.5 cm) is riveted to the head part of the helmet. It consists of a narrow horizontal plate - "shelf" and a vertical one − "flap". Top of the helmet is made of two parts - a cylindrical base ("base") and a figured tube-sleeve for plumes. The base is forged in the form of a thimble. The tube-sleeve has the form of a miniature "pot" or "vase" with a wide low neck. There are holes punched to hold the fixers of the chain mesh through the bottom edge of the helmet's crown. The latters are made in the form of A-shaped flat plaques. Analysis of the plaques revealed that they were produced at the same time with other elements of the helmet, i.e. they are not added later. It was proved that the helmet GIN 148 belongs to a special group of helmets of the Oirat-Kazakh borderland from the late Middle Ages or from the early Modern times. Currently 18 similar helmets ar known by the researchers that originate from the territory of Kazakhstan, Mongolia, Russia (Volga region, Southern Siberia) and North-Western China. A distinctive feature of helmets of this serie is a riveted four-plate crown supplemented by "skeleton"consisting of narrow overlays with a flat edge and a narrow hoop (or two hoops) placed much higher than the bottom edge of the helmet. Analysis of A-shaped chain mesh fixers showed that they can be attributed to the image of the Sanskrit syllables "ma" (executed by the letter of Lancha), traditionally included into many Buddhist mantras. Images of Sanskrit signs "ma", "om", etc. are repeatedly found on protective weapons of Oirat production (helmets, shells, etc.) dated the XVII - mid-XVIII centuries and stored in Russian and foreign museum and private collections. Specific features of the helmet from ARHM as well as Buddhist symbols in its design indicate that this head protection was made by Oirat (Jungar or Kalmyk) gunsmiths in the XVII - mid-XVIII centuries. It is very likely that later the helmet could fall into the hands of Kazakh nomads and could been used as head protection up to the mid-XIX century.