Features 1. Dual power supply mode: support 3V button battery or USB interface 5V power supply, more flexible and convenient to use. 2. practical functions: with basic arithmetic operations and color ring resistance value conversion, suitable for learning and work 3. Easy to assemble design: PCB board has clear markings, welding time 1-2 hours, suitable for beginners to practice 4. Transparent acrylic shell: beautiful and elegant, the internal circuit at a glance, enhance the desktop decorative effect 5. Automatic hibernation energy saving: long time no operation automatically enter the hibernation mode, prolong the battery service life Specification Product name: calculator kit Supply voltage: 3V button battery or USB interface 5V power supply Product size: 90*128*19mm Circuit size: 78*112mm Instructions for use Power on the default sleep mode, press the C key to enter the working mode, no operation for a long time automatically enter the sleep mode, calculation errors or over the range of the display E, in the case of two operands are 0, press the = color ring resistance calculation. Press = in case both operands are 0, the color ring resistor calculation mode will automatically identify the 4-color ring or 5-color ring. The first digit of the first position indicates the unit of , the middle one indicates the unit of k, and the bottom one indicates the unit of M. Note 1. Addition, subtraction, multiplication, division operation of negative numbers, the function of continuous calculation over the calculation range will be reported as an error, the color ring resistor resistance value conversion input the number of colors to automatically identify the 4-color ring or 5-color ring. 2. Power cord power supply and button battery can not be powered at the same time, will damage the button battery. Package Includes 1 x Calculator kit