On girodisc or other large brake kits, a caliper spacer is sometimes used to accommodate for the larger diameter rotor. When this spacer is over 7mm tall, the part of the stud that locates the caliper is not exposed anymore. The sleeves are used to accurately locate the caliper by making the tapered section the same diameter as the caliper hole.
No adapters needed for GiroDisc spacers less than 7mm thick.