The STAP-2, which was also known as the Heavy STAP, was developed for the Trade Federation prior to the Invasion of Naboo.
It sported larger laser cannons and a missile launcher. Several STAP-2 vehicles were seen to be modified with shield generators. The Heavy STAP was used to scout dangerous enemy territory and to eliminate retreating enemy forces.
Its disadvantages included less agility than the standard STAP-1 and difficulty in crossing certain types of terrain, including rivers.
Trade Federation Heavy STAPs were used during the Invasion of Naboo in 32 BBY. The resistance fighters Lieutenant Gavyn Sykes and Captain Kael stole two speeders in the Theed and escape into the countryside and destroyed many STAPs that attacking the local farmfields. Sykes later used one in the liberation of Camp Four.
A different model of Heavy STAP, more closely resembling the STAP-1, is seen in Star Wars: Galactic Battlegrounds.