These little gems were designed to prevent tangles on the cast, and help to kick your hook bait away from the lead once the rig lands on the lake bed, giving excellent presentation.
You only have to watch Underwater 8 to understand how much difference these seemingly simple little rubber sleeves made. When combined with Ali's fluorocarbon rigs, the Anti-Tangle Sleeves actually helped his rigs to reset themselves after they'd been rejected by wary fish. That meant that even though he'd been 'done' his rig was still fishing effectively, ready for the next customer!
Pictures are for illustrative purposes only and may vary from actual product.