Pilots in EVE Online can do a lot to optimize their ship loadouts for specific purposes. Many ship hulls in the game can be quite versatile depending upon which modules you choose, allowing a pilot to excel in a particular pursuit or task in EVE. Another layer of ship customization is the use of rigs, essentially devices that impart specific bonuses to a ship. These add-ons allow you to do anything from perma-running your Level 4 mission tank to pinpointing hidden exploration content. But the high costs and fact that rigs can't be removed without destroying them have ensured they're used almost exclusively on large ship classes, namely battleships, given their substantial tanks and survivability.
Pilots who prefer to fly smaller ships like frigates and cruisers will soon have more cost-effective options for tricking out their ships using small and medium rigs, to be introduced with Apocrypha 1.5 in August. Small rigs will be used on frigates, destroyers, interceptors, and interdictors, priced between 100k - 1 million ISK. Medium rigs will be installed on cruisers, industrials, and battlecruisers, at a cost between 600k ISK and 5 million ISK. These are substantially reduced prices from the game's current offerings, but these smaller rigs won't have watered down bonuses. They will provide the same benefits (and drawbacks) as the larger rigs in terms of percentages.