Must have for every Sakura D3 owner!
I used these to make a fast fix for the center belt slack of the Sakura D3 chassis by putting 2 of those under the front screw holes of the center pulley mount and 2 1 mm under the rear screw holes. By tightening up the screws, the center pulley mount goes up and back, tightening the center belt without losening the rear belt. Very cheap fix and these washers look gorgeous!
They also can be used to replace the stock plastic washers between the suspension arms and the suspension mounts. It adds extra bling to the chassis and let the suspension travel more freely because the stock plastic washers have moulding edges on them that can scratch on the suspension arms, increasing friction on the suspension. These aluminum washers are perfectly manufactured, so no friction generating edges.