DTM-501 Series consists of the DTM-551, DTM-531 and DTM-521.

Nikon introduced the new DTM-501 Series, consisting of the DTM-551, DTM-531 and DTM-521. Improved features include faster Electronic Distance Measuring (EDM), an enhanced onboard data collection system, longer distance measurement ranges of up to 4,400 meters, faster initial distance measurements of one second in the Precise Measurement mode (MSR) and the Course Tracking mode (TRK). Internal memories contain an 8,000 point capacity. Users can upload their own code lists or define Quick Codes for each key. Other features include IPX-4 all weather construction, a large LCD and ergonomic alphanumeric keyboard, and measurement displays that can be configured for user preference. (Nikon, Melville, N.Y.)