I just looked this up on the Scottish Register of Tartans website re the Leatherneck tartan:


STA ref: 3612
STWR ref: none
Designer: Hall & Macleod
Tartan date: Not Specified
Registration date: This tartan was recorded prior to the launch of The Scottish Register of Tartans.
Category: Military

Restrictions:

Registration notes: Designed by Bob Hall and R H Macleod for the U.S. Marine Corps Historical Foundation. Does not have the sanction of the Corps but is sometimes sold as the 'U.S. Marines.'
Just something to keep in mind, as far as the registration notes go the tartan is not official therefore anyone can wear it, the tartan is after all a fashion tartan, if you like get it and wear it well.