The Imperial 12GA SG is a 12-gauge shotgun shell loaded with SG buckshot, which refers to a specific size of large lead pellets (buckshot). The specific characteristics can vary slightly by manufacturer or region, but typical specifications are:

Gauge: 12-gauge
Shot Size: SG (Standard Grade) buckshot, a large pellet size
Shell Length: Commonly 70mm (2 3/4 inches)
Weight: Often around 32 to 35 grams (approximately 1 1/8 to 1 1/4 ounces) of lead shot
Pellet Count: Varies, but sources indicate potential counts of 9 to 16 pellets depending on the specific loading and hull construction
Velocity: Approximately 360 m/s (around 1180 fps) at the muzzle for some specific loads
Intended Use: Buckshot loads are typically used for hunting medium to large game, predator control (coyotes, foxes), or home defense at closer ranges (within 50 yards).

Note: "Postas" is likely the Spanish/Portuguese word for "shot" or "pellets", indicating it is a shotshell rather than a slug. Ammunition purchases generally require a valid firearms license and adherence to local regulations.