Ellen Elishewitz filed an application for a patent for the Black Box concept knife. The idea of a fixed blade with part of the blade retracted in the handle is a concept he designed back in the late '90s, which was put into production by Masters Of Defense as the Phoenix, equipped with a button lock mechanism. For this Black Box concept, he took the idea of the Phoenix and completely re-designed the entire knife, from the shape to the locking mechanism and the sheath. Then he found a manufacturer who was able to produce these for him at the quality level he wanted and at an affordable price.
The concept allows the user to carry a 4" fixed blade with part of the blade retracted in the handle and only 1.5" exposed. The sheath holds onto the tip of the blade, and as the knife is pulled out, it extends the blade. The patent-pending mechanism locks the blade open. When the lock is disengaged, the blade slides back into the handle, and the knife can be put back in the sheath (it needs to be done in this order for safer and trouble-free re-holstering). The sheath features a clip, which allows the user to secure it to garments and gear. The system allows the user to carry a 4" fixed blade in a compact package.
The Ek version is the non-ring version of the Black Box; this concept lends itself beautifully to the Ek design. If you are not familiar with the Ek brand, this knife company started by John Ek in 1942 produced combat knives for our servicemen, and these knives have been present in many armed conflicts since WWII.
Four different blade configurations are available: Dagger (no serration, partial serrations, or full serrations) and a single edge.