Begin with the electromagnetic environment. On military platforms the priority is controlling electromagnetic interference, so look for keyboards tested or certified to MIL-STD-461 for EMI, the standard that separates a defence-grade keyboard from a merely rugged one. Next, consider whether the keyboard will be used alongside night-vision equipment, as NVIS-compatible green backlighting preserves an operator's dark adaptation and image-intensifier performance in low light. Confirm the shock and vibration credentials, ideally to MIL-STD-810, where the unit is vehicle-mounted or handled in the field, and match the ingress rating from IP66 through to IP68 to the dust, spray and immersion the keyboard will face. Decide on the form factor, whether desktop, panel-mount for a console, or an OEM version for integration into a wider system, and choose an integrated force-sensing resistor or trackball where a sealed pointer with no moving parts is needed. Finally, match the connection and key layout to the existing platform and operator task.