Vintage Pickett slide rule made by Pickett & Eckel, Inc. All metal slide rule. The ES stands for Eye-Saver which refers to the yellow color. Has scales on both sides. The N in the model number indicates that the cursor is made of nylon. This was produced between 1964 and 1975. The slide rule is in excellent condition. It was used and cared for by an Aerospace Engineer in the 60s and 70s. The sturdy leather case is in great condition with a little wear and ink marks as shown in the last picture. Rare vintage scientific and engineering instrument.