For an accurate and sharp high-performance side edge choose the RaceWax hard aluminum side angle file guide. Use 87 or 3 degrees for advanced skiers/racers that need more grip/bite on the slopes. Use 88 or 2 degrees for intermediate to advanced skiers/racers and snowboarders. Use 89 or 1 degree for beginner to intermediate skiers/racers and snowboarders. Accurate tool for a precision razor-sharp side edge. Base contact area approximately 4.7 x 1.5 inch / 120 x 38 mm; metal thickness range 3-4 mm. Machined from high-quality hard aluminum with a special anodized surface treatment for tool longevity. Files/clamps purchased separately.