There are four types of weapons for the purpose of salvage that you can equip. They come in for different types depending upon what you need to salvage with them.
Standard Salvage drills and lasers (Class A), such as those you find available in Lock-N-Load, will let you break up the wrecks of average sized ships that have been destroyed in combat and are floating around the system.
Type B salvage cutters however are specifically for tackling the large mobile pirate bases known as Raids once they have been destroyed by the cooperation of many captains.
Type C salvage weapons are specifically needed for processing the alien technology of Alien Derelicts, Huge alien vessels destroyed by Gal-fed forces in Expanse systems.
Alien Wreck Lasers let you salvage wrecks of alien ships destroyed by fellow Captains in Combat.