Such levels are sometimes used with GPS receivers and depth finders. A Gerkules sonar was also fitted in addition to various radio direction finders. Donaldson LJ held that this was a case of "finders keepers". A few stud finders use ultra-wideband radar scanners. Bridges made her film debut in the movie "Finders Keepers". Tank testing of hull models was introduced and mechanical calculators as range finders. The newest stud finders in the industry implement radar technology. Triangulation range finders are exactly the opposite. This consisted of a set of tracking stations using HF/DF radio direction finders. They are sold in blue tubes with red-dot style reflector sight finders. Electronic stud finders currently come in three types&colon; edge finders, center finders, and instant finders. Meteorites brought good fortune to the finders. Like edge finders, center finders require calibration. The foundation sponsors companies like Family Finders. The photographer could choose between a pentaprism and waist-level finders.