Smooth - Smooth wheels come with a shiny coating on the riding surface that feels grippy at first, but wears away quickly.
Medium - Your classic wheel shape, versatile all-around wheel for street/park skating.
Hard Line - Hardline wheels come in a conical shape with sharp edges and an extra wide riding surface for maximum grip and control on any terrain.
99a - Offers more grip than harder wheels and more slide than softer wheels. Great for slick surfaces when you want more control.