B21 Magnification: 30x Accuracy: Without micrometer: 1.5mm With micrometer: 1.2mm N ow we are getting into the sub-order levels that I would consider as the minimum for Surveyors. The "B" series are the start for those who need high accuracy, good magnification and the option to increase the accuracy by using a micrometer. IPX4 rating. B20 Magnification: 32x Accuarcy: Without micrometer: 1.0mm With micrometer: 0.8mm There is a notable step up to this level from the B21. One of these units were sold to a company that wanted to watch concrete over a period of time. The slab was laid and before further construction could be done they had to observe any variance in the subsidence of the slab. It was an exciting event but what good came out of it was that this unit performed its duty. This level will allow you to do anything except first order levelling. In relative terms it would be a better buy than the B21. That is what sales world-wide have shown. IPX 4 rating.
	B1 & B1C Magnification: 32x Accuracy: Without micrometer: 0.8mm With micrometer: 0.5mm These units have there place but they are not waterproof or dustproof. However, for the purpose of this instrument you wouldn't use it in adverse conditions anyway. Sokkia's B1/B1C are the Top of the Line in Automatic Levels - Ultra Precise, Rugged, and Compact The B1C includes a horizontal circle with direct reading to 10' and estimation to 1'. Low IPX rating. Not suitable for excessive wet or dusty conditions.
	PL1 Magnification 40x Accuarcy: 0.2mm Estimation to 0.01mm Sokkia's PL1: First-order Precision Level. The foremost instrument in its field; free from error even under the most difficult surveying conditions, yet convenient and easy to use. The PL1 micrometer is graduated in millimeters. The tilting screw used to level the line of sight is engraved with graduations that accurately indicate the inclination, and index lines that indicate the number of turns of the tilting screw. The tilting screw is divided into 50 equal divisions, each division equaling 2'of inclination. Low IPX rating. Not suitable for excessive wet or dusty conditions.
	SDL30 Magnification: 32x Accuracy: 1mm The SDL30M now has memory installed for those not using a Data Recorder. This low-cost, user-friendly digital level is ideal for construction. Use it instead of traditional automatic levels when carrying out site preparation work, road cross- sections, or any leveling task requiring data storage using the internal memory or an SDR31/SDR33 for further processing.   Advantages include: Obtain height and distance with the touch of one key Height range 0 to 4.05m, distance range 1.6m to 80m in normal conditions (100m in good condition) Minimum resolution 0.1mm Hook up to the SDR31 or SDR33 Low-cost fiberglass bar-code staff Use as conventional automatic level with traditional graduated leveling rod. IPX4 rating.