Ensure A Powerful Jump Start For Your Vehicle With The U Part Jumper Cable Med Duty 300 Amp. This Medium Duty Jumper Cable Is Designed To Provide A Robust Connection Between Two Vehicles; Allowing For A Quick And Efficient Jump Start Process. Whether Youre Facing A Dead Battery Or Lending A Helping Hand To Another Motorist; This Jumper Cable Is A Must Have Automotive Accessory. Jumper Leads For Petrol Engines: 16 Mm 300 A And 25 Mm 400 A. Diesel Engines: 40 Mm 500 A.