The Heavy STAP, or Heavy Single Trooper Aerial Platform, came into being thanks to the Trade Federation following the Invasion of Naboo.
The Heavy STAP had bigger laser cannons and a missile launcher when compared to the STAP-1. It was deployed for scouting hazardous areas with enemy presence and for taking out enemy units in retreat.
This particular model bears a strong resemblance to the STAP-1. Be careful not to mix it up with the STAP-2 featured in Star Wars: Episode I: Battle for Naboo, as that one is also referred to as a Heavy STAP.