The new FLOW 556K L is a new variant of the popular FLOW 556K with a locking collar. In fact, the L or Lima designation is for Locking Collar, just like the 556 is for the caliber, K is for short or Kurz and FLOW is a Flow-Through design.
Here, you can see it next to a standard 556K Flow which is DMLS printed in 17-4 Stainless. Designed for toxic fume exposure mitigation,
it also offers flash reduction, sound reduction, recoil reduction, accuracy, and repeatability by its unique Flow-Through helical coil and core deflector design. It is full-auto rated and compatible on 5.56, 17 HMR, and 5.7 platforms.