Adesso Numeric USB Keypad with Built-in Calculator with Retractable Cable (AKP-160) Large LCD display. 8 calculator functional hot keys: MRC, TAB, %, MODE, M-, M+, +/- and SEND Support plug and play and hot swapping Two-Way Power System for calculator mode uses PC power, in addition to one A13 battery (LR41) Auto power off after 4 minutes from the last key entered. Selectable Rounding from among floating-point, cut off, round off and Add Mode Membrane switch with tactile feedback Defines the number of decimal places: (0,2,4,A)