Ronnie, the first manned Mercury mission the knife was attached to the hatch and was knife was lost when they blew the hatch. That is when they started putting them in the kits. And the knives made for and with the astronauts names on them had sheaths. Some of these knives were carried on missions. Now the question is, Did Grissom have his own knife packed in the kit? Who really knows. Just because NASA got the knives with no sheaths does not mean that they did not get some made later.If you will reread Mr. Gaddis's book pages 178 and 183 you will see.And check some of NASA's information sites also. The only way you will know for sure is to get a original NASA Mission Equipment Material Packing List per Mission Rules for each Mercury flight.Edit by me the oldguy.