Bones STF Locks 52mm Rosas wheels are the new signature wheel for pro skate Yonnie Cruz and are made with a substantially higher rebound urethane that is super flat spot resistant for more speed and awesome slide characteristics. Street Tech Formula is top quality urethane that offers a very fast roll speed, that grips when you need to and slides when you want to. The STF 103a (83b) durometer are the original Bones Street Tech Formula, outperforming the competition by wearing down super well, and maintaining their shape and feel for far longer. For more info read Bones Wheel Formulas Explained. The lock shape uses a radial profile lip for a better lock in to grinds on ledges and rails. The Inner lip has a tighter, sharper radius for a crispier lock in. The outter lip profile is wider with an even radial curve to give you a smoother roll when your rattling of flip tricks. The Locks also provide a little more contact patch so you can crank up the speed you take into you lines with more control and grip. For more info read Bones Wheel Shapes Explained. The 52mm wheel size offers fast acceleration and a lower rider for quicker pops and maintaining good momentum on small transition and ramps. The smaller size is great for techy street shredders and smaller sized humans. Bearing core - Center-Set so you can reverse the wheel to save the graphic and help get longer life out of your wheels as you can rotated them so they burn down evenly.