Skill Boosters can be found in the Mako Elite Shop under the name of 'Skill: <skillname>'.
Each item costs 50 mako, and boosts the according skill by one skilllevel as long as it is in inventory.
The following restrictions apply:
1. A skill can only be boosted once with an item. They do not stack multiple times on the same skill.
2. Each item will only boost a skill up to its max of 60.