Underspins work well for largemouth bass. You can rig any soft plastic you want on these baits, however, most anglers report the best success by imitating bait fish such as shad, shiners and other types of minnows.
Best Baits on an Underspin
Thinner Soft Plastic Jerkbait Minnows
Curly Tail Grubs
Curly Tail Worms