This is a set from powerslide which includes eight 78mm wheels, plus 16 ABEC-5 bearings and eight 8mm spacers. In other words a complete wheel set, ready to go. A good set for the recreational user. The advantages are that with a relatively low price you have a brand new complete wheel set with bearings and everything you need to roll. The disadvantages are that ofcourse the wheels are of lower quality than for example the FR street invaders or the Rollerblade Oxygen wheels. For someone that skates a lot such higher quality wheels would be better and last longer but for someone who just skates a few times a year this set will suffice.