  A new class of jet clustering algorithms is introduced. A criterion inspired
by successful mass-drop taggers is applied that prevents the recombination of
two hard prongs if their combined jet mass is substantially larger than the
masses of the separate prongs. This "mass jump" veto effectively results in
jets with variable radii in dense environments. Differences to existing methods
are investigated. It is shown for boosted top quarks that the new algorithm has
beneficial properties which can lead to improved tagging purity.
