Un-Pinning the bridge means to REMOVE the 2 "pins" (they are actually Allen screws), that hold the wood base in place. This makes the bridge truly "floating". But, it also means you have to re-set the intonation every time you change strings because the bridge will move (or come off). Some people use double-stick tape to prevent that from happening, but what's the point in that, if you already have a pinned bridge? Pinned bridges are good. Bar bridges with inexact intonation are not. This is why I like standard adjustable bridges. I had a bar bridge for years (a Compton), and of course my Hot Rod is pinned, thank goodness. This is why, with bar bridges, "custom" is good because string gauge matters to intonation. Even then, the Compton wasn't perfect. It was "good enough for rock and roll", but not good enough for jazzy chords up the neck (not for my ear anyway). So I had the stock rattler LOL, went to a Compton for many years and was happy with it, now have a TonePros and that's the end for me... no rattles, perfect intonation.