Dragon Radar-proof box
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Dragon Radar-proof box was created by Pilaf to hold a Dragon Ball he had found. After being bested by Son Goku and Bulma the last time around with their superior Dragon Radar, Pilaf had decided to find a way to foil any further attempts of collecting the Dragon Balls by anyone but himself. The box was made of a material that completely blocked the small amount of energy Dragon Balls give off as a signal to their location. To find the Dragon Ball located within it, Goku, Kuririn, Yamucha, Puar, and Upa had to go to Uranai Baba to learn its whereabouts. After Pilaf's plan surrounding the Dragon Radar-proof box failed, it was not seen again.