A Line-Up Problem– can occur when the edges of the hair are curling back during a shape-up. Depending on how much the hair will curl, it can cause the hairline to get taken back too far. 0-Gap Hair Line-Up (super hold spray) restrains the hairline from curling at the edges as much as possible. Now the edges are cut at their longer length for a fuller and sharper looking Line-Up. For a barber, this will leave a wider margin for error and a lot more recovery room if needed.