A "Maximum Series" bet in roulette is a type of high-stakes bet covering a sequence of numbers or a specific section of the roulette wheel. It usually involves placing the maximum allowable bet on a carefully selected set of numbers, such as neighbors or a particular series like "Voisins du Zero" or "Tiers du Cylindre." This bet strategy is often used by players who aim to cover a larger part of the wheel with the highest possible stakes, increasing the potential payout if one of their chosen numbers hits.