The K2 Electra Custom Fit inline skates are custom fit via the advanced liner that holds shape to your feet. K2's Hi-Lo Aluminum frames allow for 100mm wheels in the back, and 90mm in the front. This keeps the deck height of the skate as low as possible so that you can get the speed you're looking for, without giving up too much control. Comes stock with K2 ILQ 9 Classic Bearings. Having wheels larger in size, this K2 inline skate is considered a high-end performance skate and is designed for intermediate, if not advanced level skaters. The K2 Electra skates are more than capable of putting up a good time at an inline marathon, but are also great for open trails and longer skates (in or out of organized events). The Stability Cuff provides more support and stability than what you would might find on traditional marathon skates or even K2's Radical Series. The amount of support on the upper boot slightly adds to the weight of the boot in comparison. Personal preference dictates the amount of stability/support desired.