This is a new Aftermarket replacement for the Yamaha SR250 Exciter CDI Igniter (CDI) which has been discontinued by Yamaha.
The original ignition unit was made by OKI telecom and this number may have been stamped on it TID11-02 or TID11-04 Hitachi ( The original part is show in the photo below)
The new replacement ignition unit larger and will mount differently than the original part. (see orange colored part)
This unit has some improvements over the stock unit: