The Jelenko surveyor is distinguished by its spring-mounted horizontal arm, which allows for smooth and precise vertical and horizontal adjustments. This feature facilitates accurate determination of the height of contours, undercuts, and guiding planes in removable partial denture design. The spring mechanism provides controlled movement and stability, enhancing the clinician's ability to replicate intraoral conditions on the cast. Other surveyors like Ney, Williams, and Hanau lack this specific spring-mounted horizontal arm, making Jelenko unique in this aspect. This design improves both efficiency and accuracy during surveying procedures.

Reference: Stewart's Prosthodontics, Zarb GA, Bolender CL, Edition 5.