Your search for "Machina Armored Unit SDMM-EN021" revealed the following:
Machina Armored Unit - SDMM-EN021 - Common - Unlimited from Structure Deck: Machina Mayhem Unlimited, available at 401 Games Canada. Rarity: Common Card Text:Once per turn, when a Machine-Type monster is destroyed by battle and sent to your Graveyard, you...
Machina Armored Unit - SDMM-EN021 - Common - 1st Edition from Structure Deck: Machina Mayhem 1st Edition, available at 401 Games Canada. Rarity: Common Card Text:Once per turn, when a Machine-Type monster is destroyed by battle and sent to your...
Machina Armored Unit - SDCR-EN028 - Common - Unlimited from Structure Deck: Cyber Dragon Revolution Unlimited, available at 401 Games Canada. Rarity: Common Card Text:Once per turn, when a Machine-Type monster is destroyed by battle and sent to your Graveyard:...