Extra rillers for the HWK SpeedPro Structure Tool! Linear 0.2mm is for -10°C and colder in extremely cold and dry conditions. Linear 3mm is for wet snow +2°C and warmer. It is usually combined with other rollers (SL, SR, V 0,5 mm or V1 mm). In skating, it is mostly used only from the binding to the end of the ski. For classic skis, before and after the grip zone. Screw Left + Screw Right are for -3°C to +5°C in humid conditions. The two rollers are always used together, as this results in a diamond structure.