Do you know that the environmental conditions may cause damages to systems or machines to the point of shorten their lives and lower their performances? Grain mills, steel rolling mills, foundries, machines for electroplating processes and chemical industry , heavy industry tool machines or construction and logistic equipments are some of the so called "negative environments", characterized by huge production of dust, use of liquids, sometimes even the rain, all of which are highly damaging. Technical features: resistance gaskets are located on both sides of the ball bearing, to guarantee perfect resistance and avoid eventual infiltration from dust, humidity and fluids of various types. On the exterior side special protection “flaps”  are present which, thanks to the centrifugal effect, guarantee the expulsion of any polluting agent. Should the housing be used in particularly critical conditions such as the ambient where agricultural companies or iron and steel foundries operate, all of the housing can be supplied with interior grooving for the assembly of protective covers. The covers can be constructed in grey cast iron or in steel sheets or in plastic and are constructed in such a way as to guarantee even eventual substitution of rubber seals. They are available in the closed version or with through hole to fit different mountings on the shaft. For a better assembly the ISB bearing units are provided with setscrews with ball which offer a greater safety against loosening, allow repeated assembly and disassembly, avoid any contact corrosion and keep a lower tightening torque. All the bearings have a burnished inner ring in order to prevent locking with the shaft seals; they are pre-lubricated and can be lubricated repeatedly, except the serie CR, RB, SA, SB, which are lubricated for their lifetime.