Mitch, Excuse me I've been busy in another thread trying now to get the tar and feathers washed off . Your sheath is for the Steel Master a good sharpening tool Buck put out to steel/sharpen you knife on . The devise came with a 5" steel that telescoped out of a metal handle with a flipper locking lever . Yours looks to be in good shape maybe 1970's . The early steels were rounded at the end, later Buck made the end with a wedge . Which many of us used to open the pelvis of a deer harvested . Just cut a cedar limb to use as a mallet and place the wedge at the pelvis bridge . It was a great tool . Mine has the 137 stamped in it at the exact same place as yours . Thanks . DM