Tamiya - JR Double Aluminum Rollers w/ Rubber Rings (13-12mm) Electric Accessories Wire They allow the end user

They allow the end user to find their perfect weight bias to aid Rock Crawling

Steel cross pin inserts reduce differential case deformation by increasing the contact area with the differential case

Machined brass

Compatible with TA07 PRO chassis

By adding mounting points to the 2 diff cover holes this will help prevent snapping the 2 upper bulkhead screws off of the bulkhead

Tamiya - JR Double Aluminum Rollers w/ Rubber Rings (13-12mm) Electric Accessories Wire They allow the end userWhen a Mini 4WD machine leans during a corner section, the upper 12mm roller makes contact with the course walls and helps to stabilize your machine's positioning and keeps you on track. This Double Aluminum Roller set features rubber rings on the 12mm rollers, which provide a braking effect to produce more stable cornering action.