The ALT-25 was a blaster pistol model manufactured by BlasTech Industries

BlasTech Industries Organization Manufacturers

before the Cold War. Also know as L-12 blaster pistol, the basic model features included a magnetic adhesion grip and side-mounted rangefinder. The manufacturer sold additional components that could be used to modify the base model, such as a fire suppressor and a targeting scope. Also, the model was sold in several colors - the base model was chromium in color, other colors included bronzium-copper, steel-blue and gold.
Mandalorians

Mandalorian Organization Mandalorians

were often seen armed with ALT-25s, for example War-Master Rhigoth

Rhigoth (Human) Character Minor Characters (TOR)

used twin basic ALT-25 pistols as his favourite weapon.