Neko weights, often referred to as nail weights, have several uses. The primary one being a Neko rig, which explains why that’s its namesake. A Neko rig is basically a wacky-rigged soft plastic with a weight added to one end of the bait so it will not only sink faster but also can be dragged along the bottom with its nose down and tail up higher in the water column. But since the bait is being dragged by the middle where the hook is, it has a uniquely different action to that of a Texas rig for example.
But nail weights and Neko weights can be used for other bass fishing techniques as well. You’ll often see anglers add a nail weight to the body of a soft-plastic jerkbait or swimbait to help the lure get down deeper.