.5mm and is a good squish on a single 60cc or under.
.85mm is good for larger engines 85cc and up . The lower the stackup tolerances of the piston rock , crankpin and wristpin freeplay the lower you can go with the squish . You can go less than .5mm , all the way down to zero but it would be unlikely that an DLE engine is that tight in stack up tolerances