Bulls Mercurius Darts - Steel Tip - 90% Tungsten - AvaBulls Mercurius Darts Steel Tip 90% Tungsten Ava 15g. This new Bulls Mercurius series is the counter part of the Brutus series. The Brutus Series, known for there heavy darts, this Mercurius series is a perfect fit for players who like quality lightweight darts. Constructed from 90% tungsten, these steeltip darts offer a superior quality. The higher tungsten percentage means that the barrel need less material which also means more space in the