Up for sale is a Somewhat Rare Interesting Stethoscope, Very Good Used Condition As Shown, Please see photos for details, Original working condition, What makes this interesting is that the stem of the chestpiece has the B-D Luer-Lok patent number 1742497 which was granted in January of 1930 but is the patent number for a component of their hypodermic syringe, The chestpiece & stem are all one piece, Patents are very strict-so this may be a misprinted situation or negligent-either way it is an old stethoscope with a design that carried on for years, Great Piece!