An improved convertible backpack construction is convertible from wheeled luggage to backpack and includes a back panel with a pocket for storing attachment belts and carrying straps. The lenticular sheet has a clear coating deposited on a portion of the front surface thereof. The present invention further comprises a hinge cover which covers the hinge assembly and includes a detachable portion for allowing the main body to be folded in parallel with the base plate. under vacuum pressure of about \u221235 to \u221250 psi, and a secondary pre-curing process is performed at a temperature within a range of about 50 to 75\xb0 C. The set of calibration boards has two calibration boards located at two sides of the platform. The switch assembly may further include impedance matching lines that transform a reference impedance value to a higher value prior to switching and an impedance transformation line that provides for the reference impedance value at a distal end of the impedance transformation line.