These nifty little adapters from Shimano turn your three-bolt cycling shoes into two-bolt cycling shoes to work with SPD pedal platforms. The rubberized, elevated platform on the adapter allows you to add grip to a shoe that likely has very little and recesses the two-bolt cleat to mimic mountain bike shoes and ease walking. While the most likely application for the adapter is to use three-bolt cleats on commonly found SPD equipped gym and spin class bikes, two-bolt pedals are typically easier to unclip from than three-bolt SPD-SL pedals. New riders or riders with sensitive knees may appreciate the option. In addition to the adapter, you will need two-bolt cleats to match the two-bolt pedals to be used.