11211 (GOST 28428-90 formarly GOST 8545-75);
1212K + H212 - international designation;
1212K (DIN630) - bearing;
H212 (DIN5415) - adapter sleeve
The ball bearing consists of two rings (internal and external) and rolling elements (balls), connected with a cage - separator. Inner surface of rings has sperical form for free rings axial rotate.
Bearing with tapered inner bore and adapter sleeve;
Self-aligning ball bearing provide correct working than 2...3° axial distortion is.