WT4090 Keypad lifetime

Date: 6/19/2012
Device: WT4090
Clarify: 2623314

Hi All,

Tesco would like to know expected time that the keypad on WT4090 will work, sort of MTBF for the keypad. It does not to be that precise e.g. a number of presses to a key if it has been tested or what is expected or time how log it should hold. Obviously in standard condition, should not cout with specific usage scenario. Do we have such information or do we have an official applicable statement?

Many thanks!