As well as the latest technology, Air Zone Comfort System and ToughSider II wrap around sole and Roller Sole technology – the SP Series offers a higher quality leather selection along with larger scuff cap for increased protection on selected styles. The scuff cap and sole feature a new high density TPU for added performance life. The SP Series range comes with more advanced inner sole as standard. Poron 4000 in the heel impact area of the inner sole enhances significantly the shock absorbancy effect of Airzone. Click for technical information.