Boosters help you to complete levels in Breaker Fun 2 more easily. You can earn boosters from beating levels and completing tasks. Also, you can purchase them in the shop.
Pre-Level Boosters, you must select them BEFORE the current level begins. There are 3 of them:
Lasers will place a horizontal and a vertical laser in the empty place.
Detonator bomb will randomly replace one brick in the field. 
+5 Balls will add 5 balls with each shot in the current level.