Leofoto Brand Mounting Stud fits S4 Zeiss RF Binocular ►Fits All Zeiss RF 2018 Model. .►Weight: 28g ►Installation Instructions First, remove the battery cap o-ring & spring. . Place the o-ring and spring in the exact same location on the S4 Zeiss RF Stud and tighten the stud onto the binoculars using the provided allen wrench. ►Includes 2 Allen Wrenches ►All Metal Construction