This bearing is the one i actually use on my older model Novarossi .12 race engine. Its the exact same size aa the front steel ball bearings. Why swap a metal bearing for another? Well its simple because the original bearing as good quality as they are, are not fully sealed, so dust, dirt and water can make their way into your engine bearings and cause it to not work as they were intended too. Hey, you can always keep your original bearings for a rainy day. These bearing have a rubber seal on both side so it keeps the unwanted out. At this price its worth grabbing afew or even a packet of 10 which rcMart also sells. Overall a good product at another great price!