The FN 545 is a polymer frame striker-fired semi-automatic pistol manufactured by FN America, a division of FN Herstal. 
History.
The 545 was released in 2023 alongside the FN 510, which is chambered in 10mm Auto.
Design.
Based on the FN 509, the FN 545 is a striker-fired handgun with a stainless steel slide with ferritic nitrocarburizing finish and a polymer frame.
Black and flat dark earth (FDE) colorings are available.
The FN 545's barrel length is for the Standard Full Size (MRD) model & for the Tactical model. The backstrap of the grip accepts interchangeable inserts; one arched and one flat.
The slide has serrations on both front and back, for easy slide manipulation.
Operation.
The FN 545 features double-action operation with magazine releases and slide locks present on both sides of the gun, plus a Picatinny rail located forward of the trigger guard.
Instead of a manual safety, the 545 includes an integrated trigger safety (the articulated trigger type like the FN FNS) as part of its four passive safety systems: a striker block, a drop safety, a trigger disconnect and a trigger safety lever.
Magazines.
The FN 545 primarily uses 15-round magazines; 10-round magazines are available for states with a high-capacity magazine ban.
Ammunition.
The FN 545 is chambered in 45 ACP.
Variants.
Several variants of the FN 545 have been made available:
Tactical.
 barrel length, 15- and 18-round magazines, available in black or FDE, threaded barrel, raised sights (to accommodate a suppressor), with low-profile optics mounting system (for a red dot sight).
Standard (MRD).
 barrel length, 15-round magazines, available in black or FDE, with low-profile optics mounting system.