Neck curls is one the primary mass builder of the front neck, this exercise will thicken the sternocleidomastoid muscle, which will make your neck appear more thick and wide from the front.
For Neck curls you need just straight weight as it the simplest way to train your neck, with minimum equipment.
If you just starting your neck trainings you may think that exercise with a plate is not es effective as neck harness let me assure you.
You can easily add the first size to your neck without using any fancy neck harness.
It's actually one of the best exercise that not so easy adequately replace with neck harness.
You will receive great result with only this exercise.
Why should I train my neck? Neck exercises not only make your neck more beautiful, but also help you to strengthen your neck, so no random sneeze during shaving will cause you Herniated Disc in the neck.
It also helps you to protect your breathing paths that are more difficult to get a stiffed.
Place a hat or a small towel between your head and the plate. This will create padding between the plate and your skin which will prevent skin damage.
Watch your hands. You can use your arms as additional weight, but it always prefered to disengage them, as it much better to track the progress by increasing plate weight. Hands can interfere with this, since it is easy to help or complicate the exercise depending on the your hands position.
The key to neck training success is volume, never forget this.