. Wahl's® Color Pro® Cord/Cordless Rechargeable Beard Trimmer makes facial hair grooming easy! The colors of the guards match up with the color key on the trimmer, so you always know the correct cutting length.5mm), 3/8 (10 mm), 1/4 inch (6 mm), 5/16 inch ( 7.6 mm), 3/8 inch (9.