This is the first retractable Papermate Ball Point Pen. Made between 1950 and 1953. I put a Fisher 4 N 1 refill in this pen and it works great. These original pens are still available and one should be in your collection. Anywhere from $15.00 to $45.00 dollars. Some collectors keep them with the original refill but I like to use them. All you had to do is push the clic button in and to the side so it would catch on the rim. Very easy to operate. This pen is 64 years old and works fine. Add one to your collection.