Mecha Monday: MS-05A Zaku I Early Type from Mobile Suit Gundam

Seemed appropriate, since it was the first mobile suit the Principality of Zeon mass produced prior to the One Year War.

Gundam Wiki.

While the MS-05A Zaku I Early Type was the first mobile suit to be mass produced, it was not the first to be deployed. By the time the OYW erupted, the Zeon military had already moved on to the Zaku IIs and the Is were relegated to construction and support jobs in the rear. They were ultimately deployed near the end of that war as Zeon had lost a considerable amount of its mobile suit force.