Inspired by the the Sai, a traditional Okinawan melee weapon, the Pocket Sai is a modern implementation. Optimized for compact and safe carry, it is not far from some the Sai history, where clothing (Kimono) of the time made the Sai a concealed weapon, that would be carried in sets of 2 or 3, of which various 2 handed and throwing techniques were used.
Designed to collapse and eclipse the 'Saki' or Sai tip, the handle moves to create an integral sheath. This makes each Sai a contained solution with no need to return it to an accessory sheath. In its closed form, the Pocket Sai offers a formidable blunt striking weapon weighing about half a pound of hardened martensitic Stainless Steel.
The Traditional Sai is not typically a sharp weapon, and most formal practices focus on defense manipulations to control an opponent's weapons and offer blunt strikes. My take on this design was to give it faceted bevels and the option to fully form and grind the bevels to offer a hand ground double edged dagger version. Even in the unsharpened "traditional" version the point is very effective at penetration.
The Yoku, or side prongs are arguably the most recognized feature set of the Sai, and a significant effector in practical applications. Martial arts technique utilize the Yoku to offer opponent weapon control and highly effective pinch, hold, and puncture techniques.