Wahl's signature 5-in-1 blade is a preferred option of professional groomers around the world. The 5-in-1 blade features 5 different blade sizes - #9, #10, #15, #30, and #40 - in one convenient blade. What this means is you have 5 different cut length options that range from 2 mm down to a surgical cut length of .4 mm (or 5/64" to 3/128").