Here is some more information from Gunsholstersandgear.com:
The Px4 Storm Model D .40 S&W is a Double Action Only pistol featuring a spurless hammer and an automatic firing pin block safety with a 3-dot sight system coated in Superluminova®, a special photo sensitive material that provides luminescence for up to 30 minutes with just a short exposure to any -more- Press Release Page 2 kind of light. An integrated Picatinny rail allows for mission specific use of laser devices and illumination tools. The rotating barrel locking system reduces friction within the barrel, slide, and central block providing for a smoother operation and greater reliability. The lower barrel axis also reduces felt recoil and minimizes muzzle rise allowing officers to get back on target more quickly.