The mobile grinding tool for side-edge angles between 85° and 90° at skis + snowboards. Including grinding disc, tools for changing the disc, chargeable battery and battery charger. By using a ceramic disc, this grinder enables fast and exact re-sharpening of the side edge in steps of 0.5°. For base edge tuning between 0.5° and 2° the optional base edge tuning attachment is needed. • With MAKITA lithium-ion battery 1.500 mAh and MAKITA battery charger. • With a very short charging time of the Li-Ion battery: only approx. 20 minutes. • The lightweight lithium-ion battery enables a weight reduction of 400 grams at the Discman 4 with battery. • Including a dust magnet for collecting the metal dust during grinding. • NEW: In addition each Discman 4 is equipped with a new grinding support. This enables a larger contact surface at the base when grinding the side edge and facilitates the handling of the device at the ski.