Numeric Keypad Mechanical Function: Switch travel : 2.0+ / -0.2mm Keystroke life: 10million times Key switch elasticity: 55+ / -7g Power Requirement: Working voltage: 5.0+ / -0.25Vdc Working current: Less than 30mA Power: Less than 0.5 wt Environment and Temperature: Working temperature: 0-50degrees Working humidity: None Condensation under 20% ~ 90% humidity Specification: Product dimension: L115mm* W77mm* H13mm Key layout: 17/ 18/ 19 keys are available Product net weight: 75g Products Compatibility : Support Windows / 98 / 2000/ ME/ NT/ XP / VISTA/ WIN 7 system Support all languages versions, compatible IBM PC/ PS2/ AT/ USB/ U+ P Packing : Blister card size: 200* 100* 22mm Carton size: L530mm* W370mm* H205mm Packing method: Blister with insert card, 40pcs/ Ctn. two layers