Heavy Mech Support Platform

Level 3 DARK/Machine Union Effect
500 ATK / 500 DEF

Once per turn, you can either: Target 1 Machine monster you control; equip this card to that target, OR: Unequip this card and Special Summon it. A monster equipped with this card gains 500 ATK/DEF, also if the equipped monster would be destroyed by battle or card effect, destroy this card instead.

Rulings – Yugipedia

Printings:

Rise of Destiny: RDS-EN011 (Common) - 2004-11-20
Dark Revelation Volume 3: DR3-EN071 (Common) - 2006-11-25
Structure Deck: Machine Re-Volt: SD10-EN011 (Common) - 2007-01-17
Machina Mayhem Structure Deck: SDMM-EN012 (Common) - 2010-02-19
Geargia Rampage Structure Deck: SDGR-EN019 (Common) - 2014-10-16
Structure Deck: Seto Kaiba: SDKS-EN008 (Common) - 2016-10-20
Legendary Collection Kaiba Mega Pack: LCKC-EN022 (Ultra Rare) - 2018-03-08
Speed Duel: Battle City Box: SBCB-EN066 (Common) - 2020-11-26

Prices:

Cardmarket: 0.04 €
TCGplayer: $ 0.01