Kerckhaert SX8 Unclipped Hind. Price per Pair. Case pricing implemented on full boxes (15pr) Demand for shoes punched for City head nails brought forth the SX Series. The SX-8 is a 5/16" thick shoe with graduated widths. These shoes are used for trail, jumping, dressage, and ranch work. Punched for 5 City and Slim blade nails.