What is the IP55/IK05 standard?

IP and IK are international industrial standards referring to degrees of ‘ingress protection’ for electrical devices. IP55 standard: First digit 5x. Dust-protected. Full protection against interior injurious dust. That means dust cannot harm the operation of the phone. Second digit x5. Jet water resistant. Protected against water jets from all directions. That means water projected by a nozzle cannot harm the operation of the phone. IK05 standard: Shock proof. Phone can withstand impact of up to 0.7 joule.