File:Prototype Iron MSA idle.gifThe Prototype Iron is a Super-Rare unit, appearing in Metal Slug Attack, it is a seemingly modified version of Iron Nokana, only colored in Blue. Unlike it's original counterpart, it uses the track of Shoe & Karn, instead of wheels. It bears more close resemblance to The Iron, an another modified version of the Iron Nokana. Originally this unit was a Pre-Acquisition unit, but later became a Medal/VIP crank unit, however the latter was later then removed in the crank.