Best for... The ghd the blow dryer - radial brush size 4's maxi barrel is best for long and extra long hair, or creating lots of volume in mid-length styles. This ceramic -barrelled brush retains its heat to allow for a faster blow-dry. To use... Blast hair until it’s 80% dry. Working with medium to large sections, place the brush into the root area and direct the heat from your dryer at the barrel. Keep the tension as you move the brush through your hair directing heat at the barrel as you go.