-Scouters

Scouters were first made by the Tsfurujin Race as a way to sence the Saiyjins Power.When the war was over the Saiyan had won, and begun to use the Tsfurujin's tools such as the scouters for the Planet Trade.Once Radits arived on earth he saw that he could not get a exact KI detection from neither Picollo or Goku, because they could hide there powers.Once Vegeta arived on Earth he saw that they could also sence powerlevels without scouters.Once he arived on Planet Namek, the Nameks had destroyed ALL the scouters, but Vegeta knew he could sence where the Nameks were located.Later on that sence was one of the most imporant details in fight, because once your power level went too high it would make the scouters explode.And without the scouters you could not tell where your oppent was at or what his fighting power was.