If you want your shelves to stay up you need these!
The 16" position shelf brackets are for use with the following:
16" (25.4cm) deep Shelf & Rod shelving, only for use at the ends of the shelf, if creating a floating shelf. If your shelf is more than 36" (91.4cm) wide, then you must also use at least one shelf support bracket of a 10" or 12" position, depending on the position of the hang bar.
16" (40.6cm) deep SuperSlide shelving. If using a hang bar, 16" brackets will only be needed at the ends of the shelf when creating a floating shelf. If you shelf is 36" (91.4cm) wide or more then you will need to use 1164 - 12" position support brackets as well.
16" (40.6cm) deep Linen & CloseMesh shelving.
The shelf support brackets are needed to support the shelf and therefore you would need one every 36" (91.4cm) along the shelf's length, and also one at each end if you are creating 'open ends' or floating shelves, where 1009 - shelf support poles, or 974/980 - wall brackets have not been used.
