Pick N Pluck™ foam from Peli® is an easy, do-it-yourself system to cushion your equipment inside the case using layers of foam pre-scored in small cubes. A foam lined case will help to protect the contents so you don't have to worry about impact damage.
(Note: Some cases such as the 1700 and 1720 use solid foam instead.) Read more about Pick N Pluck foam here. Explorer Cases use a similar pre-cubed foam system.