Reasoning
Source evaluation (one opinion per source): Betafpv page favors 450 mAh (0.95) over 550 (0.90); Oscar Liang pages also favor 450 mAh (0.95) with additional 450 mention (0.90). A separate Oscar Liang article lists 300 mAh (0.95) but that is a different Cetus kit variant. Combining perspectives, 450 mAh has strongest support across independent sources, while 300 mAh appears only in one article and 550 mAh has lower confidence. Thus, 450 mAh is the best-supported value.