Crankshaft spacer washers
GruBee Inc
$3.00
Hard to find these extra thin washers 0.35 to 0.40mm thickness.
YuanDong (YD) OEM supplied for the purpose of aligning and maintaining the piston connecting rod in perfect center line position of the Cylinder thus preventing sideways wobble.
Sold in pairs of 2 called a set.
Can be used for any China doll engine.