My most treasured Korean Christmas seal item that might be of most interest to KSS members, is this used cover from Jim W. Kerr, one of the earliest members of the KSS and author of books on Korean stamps. What is really rare about this, besides it being from Jim Kerr while he was in the military in Korea, is that it has a postally used pair of the 1952 Christmas Seal, which is the most rare of the regular issued Korean Christmas seal.
The 1952 Christmas seals are rare in mint condition, and I have never seen another one used on cover. Because of the Korean War and other issues surrounding this Korean Christmas Seal, it is very hard to find.
[For more information on Korean seals including the seal catalogue see the “Seals” category on the KSS website.]