The Grease wheels are recommended for expert skating on the professional level. These wheels are composed of a 48mm wheel-hub made of stiff shockproof material and of polether polyurethane covering for a high-quality casting. Available in a 63-mm diameter with a 30-mm tread in the following varieties of hardness: 92A - for extra-slippery surfaces 95A - for slippery surfaces 97A - for regular surfaces