For clipper blades i have a number 4, (1/2) 13 mm?

Is this for cutting hair to make it short or just a trim.. i want short hair but not short enough like a buzz.. i have never cut hair with electric clippers? i usually get a 6 inch fade or the number 6 at great clips and i want to know which clipper would be best for that? also do i just shave all the way around... show more Is this for cutting hair to make it short or just a trim.. i want short hair but not short enough like a buzz.. i have never cut hair with electric clippers? i usually get a 6 inch fade or the number 6 at great clips and i want to know which clipper would be best for that? also do i just shave all the way around my head?