Oldguy why would NASA buy a sheath for Grissom's knife when it was at the bottom of the ocean? Maybe Grissom bought a sheath for it before he ever went into space. I don't know but maybe the people that recovered the capsule returned the knife to the Grissom family and then they may have donated it along with a sheath to th museum. All speculation on my part ...... Other than the fact, they didn't come with sheaths and they didn't go into space in Brown Button Sheaths. Or any other Randall sheath for that matter. This bit of info is respectfully submitted.