Four inches is a bigger target and a stronger thump — the choice when you are hunting a better class of fish and are prepared to get fewer bites for it. Big snook, bull reds and gator trout all want more bait than a slot fish does.
Pink is for stained water, low light and the tannic backwater where natural colors vanish.
The larger paddle also moves more water, which helps a fish find it in poor visibility. Fish it on a heavier sweeper or Football Jig head.