Part number  818MO6800 is on both the box and the top of the piston.   I am however unable to

Identify the models it is used in. 68mm could for example be a 2mm oversize for YAMAHA 

DT200/IT200/WR200.   Gudgeon diameter is 16mm,  and circlips are CW16.  Ring set is 2677 CD.

Original Wiseco fitting instructions are included along with a sticker.