The PL1 Precise Tilting Levels we offer are very similar in appearance and, unfortunately, have no distinct differences (except as noted below) that make it easy to tell them apart. Here are few tips that will make this easier.

1. Sokkia Japan uses three different model numbers for identification. These numbers don't appear on the instrument but are on the shipping box on the labels with the serial number.

2. Do not use the specification sticker inside the carrying case to determine the model. Sokkia sometimes uses the same sticker for all models, metric and inch.

3. You can check the graduations and number of the micrometer scale. The PL1E inch model is graduated to 0.001 inch and numbered from 0 to 50 at the 0.050 inch graduation mark (0, 5, 10, 15 etc.). The metric model is graduated 0.1 millimeters and numbered from 0 to 10 with numbers at the millimeter graduations (0,1,2,3 etc.). Page nine of the PL1 operation manual clearly shows the difference between the two. The PL1S model has a micrometer range of ±0.125 inches and is graduated to 0.001 inches. Confirming the operation of the micrometer is the best way to identify the model.

4. An additional confirmation of the model can be made by comparing the range of the optical micrometer with a ruler. It is best to have a metric ruler and inch ruler but an inch ruler can be used to check both if necessary. Attach the instrument to a tripod or alignment stand, level it using the circular bubble. We will not have to level the tubular vial for this check. Put the ruler within the focusing range of the instrument and set the micrometer to read zero. Next, turn the tilting screw so the horizontal line of the reticle is lined up with an inch or centimeter mark on the ruler. Turn the micrometer knob its full range (to 50 or 10). The reticle line should move to a 1/2 inch mark if it is the 7375-51 PL1E or to the next centimeter if it is the 7375-50 PL1. If you only have a inch ruler, the metric model will move about 3/8 of an inch.

The PL1S can be confirmed by checking that zero is in the middle of the micrometer range.

The minimum focus distance of the PL1 and PL1E is about two meters. The minimum focus of the PL1S is one foot.