In order to solve the problem of fuel pollution. the diesel fuel for power generation of marine was abandoned and shore power supply have been proposed at the historic moment. The Shore Power Supply which needs transferring 380V/50Hz to 450V/60Hz is used on shipping who need this kind of power. so effectively curbs the emissions of pollution gas into the air. https://www.spidertattooz.com/OPI-GelColor-Magnet-Tool-Mauvnetic-Poles-0-5-oz-p21159/