The IKO IRT12201 is an Inner Rings series metric inner ring intended for shell-type assembly. The supplied data identifies it for assembly with the TA1620Z bearing and lists the order number as IRT1220-1.
The product data lists a shaft diameter and inside diameter of 12 mm, an outer diameter of 16 mm, and a width of 20.5 mm. The stated material is high carbon chrome steel, also described in the supplied data as high carbon steel.
The supplied compatibility information lists TA 1620Z under assembled bearings for the TA_Z and TAM groups. No assembled bearing is listed for the TLA_Z, TLAM, YT, or YTL groups, so compatibility beyond the stated TA 1620Z reference should be verified against relevant product documentation before selection.