Help to recognize this element.

[elara]

Please some help to recognize this electronic element.

I would like to find a replacement exactly the same, but I don't know how to interpret the code that is printed on it.

The element has printed 4D-123 51M on it and was pulled out from the input filter in the primary stage of a VWR1200-D switching power supply board in a Pioneer CLD-99 laserdisc. This element is L1 in layout of board.

Distance between pins is 10,5 mm x 13 mm. Core length is 20 mm.
I am not a technician and this is all the information I have about.

Thanks you very much in advance.