The IRT12121 is an IKO inner ring in the Inner Rings product series. It is listed for shell-type use and is designed to assemble with TLA1612Z. The product order number is shown as IRT1212-1.
The supplied data identifies the IRT12121 as a metric inner ring made from high carbon chrome steel, also described in the product title as high carbon steel.
This product is categorized under Brand > IKO > Inner Rings. The supplied assembly information lists TLA 1612Z under assembled bearings for the TLA_Z / TLAM group. No corresponding assembled bearing is listed for the TA_Z / TAM or YT / YTL groups in the supplied data.