The Tropical Storm's have what many consider a flip block. I wouldn't consider the different density piece attached to the core of the Frantic, Crossroad, IQ, and IQ Tours to be a flip block because they are closer to the same dimension of the core they are attached to.
Ebonite Intl. does it a little differently and adds what looks like a basic "pancake" block to many of their cores to help increase differential. The Arson has one, the Arson Low Flare does not...
Brunswick and DV8 don't currently use them...
In the grand scheme of things, it's not that large of a factor...
High density cores? Just more marketing BS...
From the USBC Equipment Specifications and Certifications Manual -
The density of any piece/component in a ball (e.g. core, coverstock, weight block, etc.) shall
not exceed 3.80 g/mL (i.e., no pure metals or high density materials).
That's as dense as they can make a core. All that really means is a higher density core can be made smaller than a 'regular' density core. This would mean slightly less core would be drilled into with standard depth gripping holes.
