When the Astray Out Frame is damaged Lowe repairs it to the Out Frame D but, when Kaite ask him what's the difference between the Testament and the D he says the the D uses the Foam metal Armor. So my question is: What is Foam Metal Armor?
Metal foam is a real-world substance that you can look up on Google. Basically, it's metal with a bunch of gas bubbles embedded in it. This substance is obviously quite lightweight, and all the embedded bubbles help absorb external impact (kind of like bubble wrap).
And given that Out Frame D's big edge in combat (compared to its sister unit Testament) is specified to be speed and agility, it seems likely that they are indeed referring to the real-life metal foam material.
