Check the listing for details. BKK Permalock Tungsten Nail Keepers. Condition: New, Made in United States. Listed at 6.99 USD. Designed to improve the stealthy and natural appearance of your favorite soft plastics, the BKK Permalock Tungsten Nail Keepers are ideal for rigging most vertical eyelet worm of swimbait hooks. The keepers themselves are designed to be twisted onto the hook eyelet much like a spring hitch-hiker, while your soft plastic is rigged through the insertion of the nose much like a nail weight. This approach hides the weight, offers a more natural gliding action, and simply streamlines your presentation for best performance. Each keeper is embossed with its weight for easy identification and is outfitted with a fluorocarbon retainer to lock soft baits in place. Its tungsten construction provides a reduced size to weight ratio, allowing smaller softbaits to be rigged and reduced tearing overall.