Electrical machine comprising a first item having a male portion and a second item having a female portion. The male and female portions have a shape adapted to each other such that the male portion can be fitted into the female portion. The male and/or female portion is formed as a stack of sheets comprising standard sheets and protruding sheets. The "male" standard sheets substantially fits into the female portion and the "male" protruding sheets are larger than the female portion such that, in use, said protruding sheets are deformed during insertion of the male portion into the female portion. The "female" standard sheets have an opening into which the male portion substantially fits, and the "female" protruding sheets have an opening smaller than the male portion such that, in use, said protruding sheets are deformed during insertion of the male portion into the opening of the female portion.