Shelf End Supports by ISS Designs are used to support shelves between ISS or Quad Poles. You may mount the SES at any point along the pole using the ¼-20 mounting screw. Use two SES for each shelf. Secure wood shelves to the shelf end supports via the two screw holes. Choose SES with retaining pins for use with the aluminum shelves. Add the stick-on bumpers option when using glass shelves.