The 6203 ZZ C3 E NSK is a ball bearing manufactured by NSK with an inner diameter of 17mm, an outer diameter of 40mm, and a width of 12mm. It is made of bearing steel and has a C3 radial internal clearance, which means it has a larger radial clearance than standard bearings. This makes the bearing more tolerant to misalignment of the inner and outer ring. The bearing also has two metal shields on either side to keep out dirt and debris, and has the ZZ designation, which indicates that it has been pre-lubricated at the factory and is ready for immediate use. This bearing is suitable for use in a variety of applications, including automotive, agriculture, and power transmission.