TDK TFSC06054125-2113A1X Directional Coupler- "X" suffix

When looking at TFSC06054125-2113A1X Thin-Film Directional Coupler from TDK, there is a suffix digit “X”. What does this suffix call out?

“X” is a TDK internal identifying mark and denotes Laser Marking. This was implemented in April of 2016 as an improvement. Prior to laser, screen printing was employed.

Applicable Part Numbers

TFSC06054125-2113A1X
TFSC06054125-2120A1X

445-175595-1-ND
445-175595-2-ND
445-175595-6-ND

445-181441-1-ND
445-181441-2-ND
445-181441-6-ND