The rings were first appeared in HF004 by William Furno, Mark Surge and Natalie Breez in the Assembly Tower. Even though we see in the episode HF003 that the heroes have jet packs, the Anti-Gravity Rings are supposedly equipped on each new hero, as stated by Furno. The three rookies accidentally annoy Professor Nathaniel Zib when using these devices as he is monitoring Alpha Team's progress against Von Nebula's henchmen.
The rings were again used inside the black hole created by Von Nebula as Stormer and Furno were sucked in the dark vortex. While these rings did keep the Heroes floating, this didn't seem to matter since Stormer and Furno could apparently climb the 'walls' of the black hole. Furno later comes up with the idea to super heat the vortex with these gravity rings. Scientifically, this concept shouldn't be possible as super heating has nothing to do with space, rather it is about creating a massive reaction to extremely hot water. Still, despite this oversight, the plan worked....somehow.