These lightweight 13mm Aluminum Ball-Race Rollers function superb durability and so are built with 520 ball bearings available smooth rotation. Also, these rollers have less friction from the program walls and can be used for both front side and back roller setups. This type of variation uses parts that have a weight reduced total of around 30per cent due to their kind and newly-bored holes. 13mm Aluminum Ball-Race Roller x2 Attachment screws included. Suitable for all Mini 4WD and Mini 4WD PRO framework products. Some chassis and numbers could need modification.