Abstract: An applicator for use in connection with a retaining ring supply, which comprises a plurality of retaining rings detachably connected to each other so as to form a strip. The applicator is in the form of a sheath having a flat passage therethrough extending in the longitudinal direction of the sheath and being dimensioned to slidably receive and guide therethrough a strip of retaining rings. The strip has at least one window in at least one of its wide sides, which window leads from the outside surface of the sheath into the flat passage and is so dimensioned as to permit a finger, for instance, a thumb of a person to pass through said window easily and to engage a strip of retaining rings in said sheath to selectively advance the same by one ring at a time, so as to have one ring at a time project from one end of the applicator.