Copper Carapace is a common Artifact — Equipment card from Mirrodin Besieged (MBS), collector number 102. Current market price: $0.10 (foil $0.36), TCGplayer market prices via Scryfall.
Equipped creature gets +2/+2 and can't block. Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)