Designation:

NA4903 2RS (DIN617, ISO1206, ISO492);
4244903 (GOST 520)

Design:

The bearing consists of two rings (internal and massive external) and rolling elements (needle cylindrical rollers), connected with a cage.
The name of bearing NA4903 2RS w/o inner ring is

Features:

integrated protective contact seal;
the outer ring with the rollers and cage assembly can be separated from the inner ring.