Navy dog tags history: WW2 dogtags were oval shaped and made of Monel metal (a nickel and copper alloy) and had the right index fingerprint of the seaman acid etched onto the back of ID tag. This shape dog tag and fingerprint etching was discontinued in 1944 shortly after WWII.
The official US Navy Seal ID tag now uses the same M-1967 type military dog tag as the other branches of the US Military. The US Navy and the Seals use the same unique dogtags format for their ID tag sets and generally only have the ID tag information on every other line. The middle line has the US Social Security number immediately followed by ‘USN’ which is then followed by 1 space and an abbreviated blood type. As an example A POS is abbreviated to ‘AP’, O NEG is ‘ON’, and B would remain ‘B’. The last line contains the religious preference. The Navy dog tags format is identical to the Seal ID tag format.
The black dogtag silencer is standard on all military ID tags although sea blue dogtag silencers are always an option.