The Holmenkol Ergo Semi is fantastic value and the easiest way to sharpen your side edge. Fixed at 89 Degrees (1 Degree) and comes with the Cross Mini File HM20521.
The Holmenkol Ergo Profi side edger includes a Cross file mini and this tool can sharpen your side edges from 90 to 85 degrees in 1/2 degree increments.