Magnet Release

The Third Kazekage's unnamed kekkei genkai allowed him to convert chakra into magnetic forces. The Third studied the abilities of a previous host of the One-Tailed Shukaku and learned to imitate the power to control sand. However, when he imitated sand techniques, he incorporated iron powder instead, thanks to his special magnetic powers. He could use it to crush his opponents or even mold the sand into weapons. This Iron Sand can also clot up the joints of puppets, making them useless in battle as long as the Third Kazekage's magnetic field was in effect.

When the Third Kazekage was turned into a Human Puppet, Sasori gained access to the Iron Sand weapons and imbued the sand with his poison, increasing its lethality. The puppet was later destroyed by Sakura Haruno and Sasori's grandmother, Chiyo. As the Third Kazekage's ability to convert chakra into magnetic fields was unique to himself, when his puppet form was destroyed, the kekkei genkai became lost forever.

Trivia
In the anime's Land of Vegetables arc, one of the main villains Jiga had the ability to magnetize his body and other metallic objects which he gained from ingesting iron at an early age. He could use his magnetism to disrupt the electrical impulses in the brain, effectively blocking a person's entire nervous system from functioning. He was also able to rip metallic ore and rocks from his environment to make makeshift projectiles to overwhelm an opponent. He turns this ability on and off by slapping his stomach. This ability had a glaring weakness to those who could exploit it: occasionally, during the course of a battle, he had to pause to stop the flow of magnetism. If he remained the ability on for too long, he would attract all nearby ferrous objects against his will.