blade open on most clippers adds a .5 guard to whatever guard you are using. If youre using a JRL its more like .7 and the andis master blade open is equivalent to a 1 guard pretty much. MOST CLIPPERS though open lever is same as the .5 guard, so whatever guard youre using (lets say a 1 guard) would be 1.5 with the lever open and a true 1 with the lever closed.