... diameter (OD), inside diameter (ID) and pitch, and a perfect helical surface which is normal ... the axis. This will improve the efficiency of screw conveyers, blenders, piling machines etc..Product Advantage ... of the right sizes of OD, ID, PITCH, and perfect helical surface which is right ... maximum thickness is 40mm.Product Usage:Apply to screw conveyers, blenders, pile drivers, drilling machines etc ...