Cast-iron housing units serve as elements of the so called bearing units. These units are formed together with all kinds of insert ball bearings. Housing units can be divided into three types: P, F and T. P-type housings have fixing bores pointing out at right angle to the shaft axis, and they are commonly called “standing” housing units, whereas in the PA-version bores are made in the housing itself and in the Atype they are located in the housing’s flanges. The fixing bores of F-type housing units are arranged parallel to the shaft axis. Square-shaped F-type has four bores, FL-type shaped as an extended ellipse has two fixing bores and the circular FC-type housing unit has four fixing bores. The most specific features has the T-type housing unit, called a tension-fixing housing. T-shape and the ability of adjusting the tension through a special fixing are the most distinguishing features of this housing unit. All housings are made of modified green cast iron and equipped with a valve delivering grease, whereas one shall pay special attention to the proper placement of the lubricating groove and bore in the mounted bearing. The designation structure of bearing units’ symbols the system of creating designations for ready-to-use bearing units bases on the rule of combining the symbols of individual parts of the housing unit and bearing itself. CRAFT bearings housings can be filled with 2 types of insert bearing UC and UK.