Part identity and production status
The BLM15BD121SZ1D is a ferrite bead from Murata Electronics, part of the BLM15BD series, used for EMI suppression in power and signal lines.
Package and assembly fit
The base product number BLM15BD identifies the 0402 (1005 metric) footprint, so the PCB land pattern and stencil aperture match the standard Murata layout for this series.