This is an illegal module commonly used for modifying pistols.
How to Obtain[]
Only Smugglers can be rewarded those.
Illegal Pistol Modules or IPMs, are given as a stackable No-Trade reward for Tier 3 Illicit Goods missions (the ones that require five contraband items) and Tier 4 or 5 normal Smuggler missions and Illicit Goods missions.
Since Game Update 16, some of those can be found sometimes in a Crate of Components obtained upon completion of a Piracy event.
How to Use[]
Only Smugglers can use those.
Once you've got your first IPM, there is an extra conversation option on the "Off the Books" Junk Dealer that grants the 100 Illegal Pistol Modules quest. Collecting 100 IPMs will allow you to trade them for a DL-T Heavy Blaster Pistol schematic.
Additionally, a smuggler can consume one IPM through the Modify Pistol ability to benefit from a decent Pistol Damage bonus. Modifying your pistol will result in a cool animation where the smuggler loads his pistol barrel with bullets.