Maintain the EDGE Hockey player ice skate 1/2" radius of hollow sharpener is for adult skaters. See our 3/8" model for lighter players. Maintain the EDGE is the only handheld hockey player skate sharpener on the market that automatically turns the sharpening stone to promote even wear for more consistent results. This is an essential feature for a long-lasting and effective sharpener. It's what gives our products an extra EDGE. Our sharpener cuts the hollow just like a powered grinder, features adjustable thumbscrews that keep the stone centered (which is essential to match the blade you have and to even out the edges), has an industrial hard plastic handle that will not scratch or dull your blade and a super-abrasive diamond grit stone to cut the hollow, giving the longest life available. A convenient deburring stone is attached to the back of the sharpener. It's the only sharpener on the market that cuts the hollow and deburs the edges all in one convenient tool. Please note: Our sharpeners are designed for hockey player skates only, and are not intended for use on goalie skates or figure skates. Additional note about sizing: Our 1/2" tool grinds a 1/2" hollow. Since burrs left on skates make the skate feel dull, however, those who aren't as meticulous about cleaning up the edge may find our 3/8" sharpener to be more to their liking.