Over the course of the game you will receive many En Cap(S) or energy capsule smalls. You may be tempted to spend them every time you get ten. Instead, save all of them and when you get to Diggins Rock you should have at least 40 and can make a Double Booster. The Double Booster is one of the best parts. It boosts all of your mobile suits stats, including starting EN. To help you get 40. fight the Zakus at the beginning of the game periodically. This will help if you want to make a second double booster.