Focusing coils were components used in blaster weaponry. The coils helped the weapon maintain a cohesive blaster bolt during the firing process. Blasters such as the Defender sporting blaster pistol had focusing coils in their final stage collimator barrels, while weapons such as the T-21 light repeating blaster and the E-Web heavy repeating blaster had the coils spread along the length of the barrel.
- The Essential Guide to Weapons and Technology